Impish gives 10% Defense at the cost of Sp. Attack. Physical walls that rely on Body Slam, Knock Off, or U-turn over special coverage will want this. Ho-Oh, Ting-Lu, Giratina, and others all run Impish in competitive play.
Impish raises Defense by 10% and lowers Sp. Attack by 10%. Physical walls that rely on physical or status moves. 100 Pokemon competitively run this nature.
| # | Pokemon | Tier | Role | Ability | +Def | -SpA | Spe |
|---|---|---|---|---|---|---|---|
| 1 | Ho-Oh FIRE | S | Bulky Support | Regenerator | 90+14 | 110-13 | 90 |
| 2 | Ting-Lu DARKGROUND | S | Bulky Support | Vesselofruin | 125+17 | 55-8 | 45 |
| 3 | Giratina GHOSTDRAGON | S | Bulky Support | Pressure | 120+17 | 100-12 | 90 |
| 4 | Mudbray GROUND | A | Utility | Stamina | 70+12 | 45-7 | 45 |
| 5 | Rhydon GROUNDROCK | A | Bulky Support | Reckless | 120+17 | 45-7 | 40 |
| 6 | Dondozo WATER | A | Bulky Support | Unaware | 115+16 | 65-9 | 35 |
| 7 | Skarmory STEEL | A | Bulky Support | Sturdy | 140+19 | 40-6 | 70 |
| 8 | Sandslash GROUND | A | Bulky Support | Sandrush | 110+16 | 45-7 | 65 |
| 9 | Mudsdale GROUND | A | Bulky Support | Stamina | 100+15 | 55-8 | 35 |
| 10 | Donphan GROUND | A | Bulky Support | Sturdy | 120+17 | 60-8 | 50 |
| 11 | Zygarde DRAGONGROUND | A | Bulky Support | Powerconstruct | 121+17 | 81-11 | 95 |
| 12 | Regirock ROCK | A | Bulky Support | Clearbody | 200+25 | 50-7 | 50 |
| 13 | Groudon GROUND | A | Bulky Support | Drought | 140+19 | 100-12 | 90 |
| 14 | Flygon GROUNDDRAGON | A | Bulky Support | Levitate | 80+13 | 80-10 | 100 |
| 15 | Alomomola WATER | A | Bulky Support | Regenerator | 80+13 | 40-6 | 65 |
| 16 | Uxie PSYCHIC | A | Bulky Support | Levitate | 130+18 | 75-10 | 95 |
| 17 | Metagross STEELPSYCHIC | A | Physical Tank | Clearbody | 130+18 | 95-12 | 70 |
| 18 | Snorlax NORMAL | A | Bulky Support | Gluttony | 65+11 | 65-9 | 30 |
| 19 | Hitmontop FIGHTING | A | Bulky Support | Intimidate | 95+14 | 35-6 | 70 |
| 20 | Goodra DRAGON | A | Bulky Support | Sapsipper | 70+12 | 110-13 | 80 |
| 21 | Rhyperior GROUNDROCK | A | Bulky Support | Solidrock | 130+18 | 55-8 | 40 |
| 22 | Diancie ROCKFAIRY | A | Bulky Support | Clearbody | 150+20 | 100-12 | 50 |
| 23 | Torkoal FIRE | A | Bulky Support | Shellarmor | 140+19 | 85-11 | 20 |
| 24 | Ferrothorn GRASSSTEEL | B | Bulky Support | Iron Barbs | 131+18 | 54-8 | 20 |
| 25 | Hippowdon GROUND | B | Bulky Support | Sand Stream | 118+17 | 68-9 | 47 |
| 26 | Corviknight STEEL | B | Bulky Support | Pressure | 105+15 | 53-8 | 67 |
| 27 | Chesnaught GRASSFIGHTING | B | Bulky Support | Bulletproof | 122+17 | 74-10 | 64 |
| 28 | Grimmsnarl DARKFAIRY | B | Bulky Support | Prankster | 65+11 | 95-12 | 60 |
| 29 | Mandibuzz DARK | B | Bulky Support | Overcoat | 105+15 | 55-8 | 80 |
| 30 | Quagsire WATERGROUND | B | Bulky Support | Unaware | 85+13 | 65-9 | 35 |
| 31 | Gliscor GROUND | B | Bulky Support | Poisonheal | 125+17 | 45-7 | 95 |
| 32 | Gligar GROUND | B | Bulky Support | Immunity | 105+15 | 35-6 | 85 |
| 33 | Garganacl ROCK | B | Bulky Support | Purifyingsalt | 130+18 | 45-7 | 35 |
| 34 | Trapinch GROUND | B | Utility | Arenatrap | 45+9 | 45-7 | 10 |
| 35 | Altaria DRAGON | B | Bulky Support | Natural Cure | 90+14 | 70-9 | 80 |
| 36 | Orthworm STEEL | B | Bulky Support | Eartheater | 145+19 | 60-8 | 65 |
| 37 | Buzzwole BUGFIGHTING | B | Bulky Support | Beastboost | 139+19 | 53-8 | 79 |
| 38 | Araquanid WATERBUG | B | Bulky Support | Waterbubble | 92+14 | 50-7 | 42 |
| 39 | Forretress BUGSTEEL | B | Bulky Support | Sturdy | 140+19 | 60-8 | 40 |
| 40 | Registeel STEEL | B | Bulky Support | Clearbody | 150+20 | 75-10 | 50 |
| 41 | Brute Bonnet GRASSDARK | B | Bulky Support | Protosynthesis | 99+15 | 79-10 | 55 |
| 42 | Avalugg ICE | B | Bulky Support | Sturdy | 184+23 | 44-7 | 28 |
| 43 | Sandaconda GROUND | B | Bulky Support | Shedskin | 125+17 | 65-9 | 71 |
| 44 | Clodsire POISONGROUND | B | Bulky Support | Waterabsorb | 60+11 | 45-7 | 20 |
| 45 | Swampert WATERGROUND | B | Bulky Support | Torrent | 90+14 | 85-11 | 60 |
| 46 | Umbreon DARK | B | Bulky Support | Synchronize | 110+16 | 60-8 | 65 |
| 47 | Shuckle BUGROCK | B | Bulky Support | Sturdy | 230+28 | 10-3 | 5 |
| 48 | Tentacruel WATERPOISON | B | Bulky Support | Liquidooze | 65+11 | 80-10 | 100 |
| 49 | Breloom GRASSFIGHTING | B | Bulky Support | Technician | 80+13 | 60-8 | 70 |
| 50 | Dusknoir GHOST | B | Bulky Support | Frisk | 135+18 | 65-9 | 45 |
| 51 | Weezing POISON | B | Bulky Support | Levitate | 120+17 | 85-11 | 60 |
| 52 | Klefki STEELFAIRY | B | Bulky Support | Prankster | 91+14 | 80-10 | 75 |
| 53 | Braviary NORMAL | B | Bulky Support | Defiant | 75+12 | 57-8 | 80 |
| 54 | Kommo-o DRAGONFIGHTING | B | Bulky Support | Overcoat | 125+17 | 100-12 | 85 |
| 55 | Electivire ELECTRIC | B | Utility | Motordrive | 67+11 | 95-12 | 95 |
| 56 | Scolipede BUGPOISON | B | Bulky Support | Speed Boost | 89+14 | 55-8 | 112 |
| 57 | Eelektross ELECTRIC | B | Bulky Support | Levitate | 80+13 | 105-13 | 50 |
| 58 | Torterra GRASSGROUND | B | Bulky Support | Overgrow | 105+15 | 75-10 | 56 |
| 59 | Leafeon GRASS | B | Bulky Support | Chlorophyll | 130+18 | 60-8 | 95 |
| 60 | Empoleon WATERSTEEL | B | Bulky Support | Torrent | 88+14 | 111-14 | 60 |
| 61 | Overqwil DARKPOISON | B | Bulky Support | Intimidate | 95+14 | 65-9 | 85 |
| 62 | Drednaw WATERROCK | B | Bulky Support | Strongjaw | 90+14 | 48-7 | 74 |
| 63 | Lapras WATERICE | B | Bulky Support | Waterabsorb | 80+13 | 85-11 | 60 |
| 64 | Tinkaton FAIRYSTEEL | B | Bulky Support | Mold Breaker | 77+12 | 70-9 | 94 |
| 65 | Regigigas NORMAL | B | Bulky Support | Slowstart | 110+16 | 80-10 | 100 |
| 66 | Primeape FIGHTING | B | Bulky Support | Defiant | 60+11 | 60-8 | 95 |
| 67 | Murkrow DARK | B | Bulky Support | Prankster | 42+9 | 85-11 | 91 |
| 68 | Smeargle NORMAL | B | Bulky Support | Owntempo | 35+8 | 20-4 | 75 |
| 69 | Qwilfish WATERPOISON | B | Bulky Support | Intimidate | 85+13 | 55-8 | 85 |
| 70 | Cobalion STEELFIGHTING | B | Bulky Support | Justified | 129+18 | 90-11 | 108 |
| 71 | Sableye DARKGHOST | C | Bulky Support | Prankster | 75+12 | 65-9 | 50 |
| 72 | Ditto NORMAL | C | Bulky Support | Imposter | 48+10 | 48-7 | 48 |
| 73 | Dachsbun FAIRY | C | Bulky Support | Wellbakedbody | 115+16 | 50-7 | 95 |
| 74 | Swalot POISON | C | Bulky Support | Stickyhold | 83+13 | 73-10 | 55 |
| 75 | Dhelmise GHOSTGRASS | C | Bulky Support | Steelworker | 100+15 | 86-11 | 40 |
| 76 | Nosepass ROCK | C | Bulky Support | Sturdy | 135+18 | 45-7 | 30 |
| 77 | Hippopotas GROUND | C | Bulky Support | Sand Stream | 78+13 | 38-6 | 32 |
| 78 | Steelix STEELGROUND | C | Bulky Support | Rockhead | 200+25 | 55-8 | 30 |
| 79 | Runerigus GROUNDGHOST | C | Bulky Support | Wanderingspirit | 145+19 | 50-7 | 30 |
| 80 | Klawf ROCK | C | Bulky Support | Regenerator | 115+16 | 35-6 | 75 |
| 81 | Pineco BUG | C | Bulky Support | Sturdy | 90+14 | 35-6 | 15 |
| 82 | Aggron STEELROCK | C | Bulky Support | Rockhead | 180+23 | 60-8 | 50 |
| 83 | Toxicroak POISONFIGHTING | C | Bulky Support | Dryskin | 65+11 | 86-11 | 85 |
| 84 | Miltank NORMAL | C | Bulky Support | Thickfat | 105+15 | 40-6 | 100 |
| 85 | Trevenant GHOSTGRASS | C | Bulky Support | Harvest | 76+12 | 65-9 | 56 |
| 86 | Wooper WATERGROUND | C | Bulky Support | Unaware | 45+9 | 25-5 | 15 |
| 87 | Orbeetle BUGPSYCHIC | C | Bulky Support | Frisk | 110+16 | 80-10 | 90 |
| 88 | Tinkatuff FAIRYSTEEL | C | Bulky Support | Mold Breaker | 55+10 | 45-7 | 78 |
| 89 | Pincurchin ELECTRIC | C | Bulky Support | Electric Surge | 95+14 | 91-12 | 15 |
| 90 | Dewgong WATERICE | C | Bulky Support | Thickfat | 80+13 | 70-9 | 70 |
| 91 | Swellow NORMAL | C | Bulky Support | Guts | 60+11 | 75-10 | 125 |
| 92 | Wobbuffet PSYCHIC | C | Bulky Support | Shadowtag | 58+11 | 33-6 | 33 |
| 93 | Cradily ROCKGRASS | C | Bulky Support | Stormdrain | 97+14 | 81-11 | 43 |
| 94 | Dragonair DRAGON | C | Bulky Support | Shedskin | 65+11 | 70-9 | 70 |
| 95 | Crustle BUGROCK | C | Bulky Support | Sturdy | 125+17 | 65-9 | 45 |
| 96 | Gourgeist GHOSTGRASS | C | Bulky Support | Frisk | 122+17 | 58-8 | 84 |
| 97 | Druddigon DRAGON | C | Bulky Support | Rough Skin | 90+14 | 60-8 | 48 |
| 98 | Falinks FIGHTING | C | Bulky Support | Defiant | 100+15 | 70-9 | 75 |
| 99 | Hakamo-o DRAGONFIGHTING | D | Bulky Support | Bulletproof | 90+14 | 65-9 | 65 |
| 100 | Fidough FAIRY | D | Bulky Support | Owntempo | 70+12 | 30-5 | 65 |
Ho-Oh
FIRE
Role
Bulky SupportAbility
Regenerator+Def
90 +14Spe
90Ting-Lu
DARK GROUND
Role
Bulky SupportAbility
Vesselofruin+Def
125 +17Spe
45Giratina
GHOST DRAGON
Role
Bulky SupportAbility
Pressure+Def
120 +17Spe
90Mudbray
GROUND
Role
UtilityAbility
Stamina+Def
70 +12Spe
45Rhydon
GROUND ROCK
Role
Bulky SupportAbility
Reckless+Def
120 +17Spe
40Dondozo
WATER
Role
Bulky SupportAbility
Unaware+Def
115 +16Spe
35Skarmory
STEEL
Role
Bulky SupportAbility
Sturdy+Def
140 +19Spe
70Sandslash
GROUND
Role
Bulky SupportAbility
Sandrush+Def
110 +16Spe
65Mudsdale
GROUND
Role
Bulky SupportAbility
Stamina+Def
100 +15Spe
35Donphan
GROUND
Role
Bulky SupportAbility
Sturdy+Def
120 +17Spe
50Zygarde
DRAGON GROUND
Role
Bulky SupportAbility
Powerconstruct+Def
121 +17Spe
95Regirock
ROCK
Role
Bulky SupportAbility
Clearbody+Def
200 +25Spe
50Groudon
GROUND
Role
Bulky SupportAbility
Drought+Def
140 +19Spe
90Flygon
GROUND DRAGON
Role
Bulky SupportAbility
Levitate+Def
80 +13Spe
100Alomomola
WATER
Role
Bulky SupportAbility
Regenerator+Def
80 +13Spe
65Uxie
PSYCHIC
Role
Bulky SupportAbility
Levitate+Def
130 +18Spe
95Metagross
STEEL PSYCHIC
Role
Physical TankAbility
Clearbody+Def
130 +18Spe
70Snorlax
NORMAL
Role
Bulky SupportAbility
Gluttony+Def
65 +11Spe
30Hitmontop
FIGHTING
Role
Bulky SupportAbility
Intimidate+Def
95 +14Spe
70Goodra
DRAGON
Role
Bulky SupportAbility
Sapsipper+Def
70 +12Spe
80Rhyperior
GROUND ROCK
Role
Bulky SupportAbility
Solidrock+Def
130 +18Spe
40Diancie
ROCK FAIRY
Role
Bulky SupportAbility
Clearbody+Def
150 +20Spe
50Torkoal
FIRE
Role
Bulky SupportAbility
Shellarmor+Def
140 +19Spe
20Ferrothorn
GRASS STEEL
Role
Bulky SupportAbility
Iron Barbs+Def
131 +18Spe
20Hippowdon
GROUND
Role
Bulky SupportAbility
Sand Stream+Def
118 +17Spe
47Corviknight
STEEL
Role
Bulky SupportAbility
Pressure+Def
105 +15Spe
67Chesnaught
GRASS FIGHTING
Role
Bulky SupportAbility
Bulletproof+Def
122 +17Spe
64Grimmsnarl
DARK FAIRY
Role
Bulky SupportAbility
Prankster+Def
65 +11Spe
60Mandibuzz
DARK
Role
Bulky SupportAbility
Overcoat+Def
105 +15Spe
80Quagsire
WATER GROUND
Role
Bulky SupportAbility
Unaware+Def
85 +13Spe
35Gliscor
GROUND
Role
Bulky SupportAbility
Poisonheal+Def
125 +17Spe
95Gligar
GROUND
Role
Bulky SupportAbility
Immunity+Def
105 +15Spe
85Garganacl
ROCK
Role
Bulky SupportAbility
Purifyingsalt+Def
130 +18Spe
35Trapinch
GROUND
Role
UtilityAbility
Arenatrap+Def
45 +9Spe
10Altaria
DRAGON
Role
Bulky SupportAbility
Natural Cure+Def
90 +14Spe
80Orthworm
STEEL
Role
Bulky SupportAbility
Eartheater+Def
145 +19Spe
65Buzzwole
BUG FIGHTING
Role
Bulky SupportAbility
Beastboost+Def
139 +19Spe
79Araquanid
WATER BUG
Role
Bulky SupportAbility
Waterbubble+Def
92 +14Spe
42Forretress
BUG STEEL
Role
Bulky SupportAbility
Sturdy+Def
140 +19Spe
40Registeel
STEEL
Role
Bulky SupportAbility
Clearbody+Def
150 +20Spe
50Brute Bonnet
GRASS DARK
Role
Bulky SupportAbility
Protosynthesis+Def
99 +15Spe
55Avalugg
ICE
Role
Bulky SupportAbility
Sturdy+Def
184 +23Spe
28Sandaconda
GROUND
Role
Bulky SupportAbility
Shedskin+Def
125 +17Spe
71Clodsire
POISON GROUND
Role
Bulky SupportAbility
Waterabsorb+Def
60 +11Spe
20Swampert
WATER GROUND
Role
Bulky SupportAbility
Torrent+Def
90 +14Spe
60Umbreon
DARK
Role
Bulky SupportAbility
Synchronize+Def
110 +16Spe
65Shuckle
BUG ROCK
Role
Bulky SupportAbility
Sturdy+Def
230 +28Spe
5Tentacruel
WATER POISON
Role
Bulky SupportAbility
Liquidooze+Def
65 +11Spe
100Breloom
GRASS FIGHTING
Role
Bulky SupportAbility
Technician+Def
80 +13Spe
70Dusknoir
GHOST
Role
Bulky SupportAbility
Frisk+Def
135 +18Spe
45Weezing
POISON
Role
Bulky SupportAbility
Levitate+Def
120 +17Spe
60Klefki
STEEL FAIRY
Role
Bulky SupportAbility
Prankster+Def
91 +14Spe
75Braviary
NORMAL
Role
Bulky SupportAbility
Defiant+Def
75 +12Spe
80Kommo-o
DRAGON FIGHTING
Role
Bulky SupportAbility
Overcoat+Def
125 +17Spe
85Electivire
ELECTRIC
Role
UtilityAbility
Motordrive+Def
67 +11Spe
95Scolipede
BUG POISON
Role
Bulky SupportAbility
Speed Boost+Def
89 +14Spe
112Eelektross
ELECTRIC
Role
Bulky SupportAbility
Levitate+Def
80 +13Spe
50Torterra
GRASS GROUND
Role
Bulky SupportAbility
Overgrow+Def
105 +15Spe
56Leafeon
GRASS
Role
Bulky SupportAbility
Chlorophyll+Def
130 +18Spe
95Empoleon
WATER STEEL
Role
Bulky SupportAbility
Torrent+Def
88 +14Spe
60Overqwil
DARK POISON
Role
Bulky SupportAbility
Intimidate+Def
95 +14Spe
85Drednaw
WATER ROCK
Role
Bulky SupportAbility
Strongjaw+Def
90 +14Spe
74Lapras
WATER ICE
Role
Bulky SupportAbility
Waterabsorb+Def
80 +13Spe
60Tinkaton
FAIRY STEEL
Role
Bulky SupportAbility
Mold Breaker+Def
77 +12Spe
94Regigigas
NORMAL
Role
Bulky SupportAbility
Slowstart+Def
110 +16Spe
100Primeape
FIGHTING
Role
Bulky SupportAbility
Defiant+Def
60 +11Spe
95Murkrow
DARK
Role
Bulky SupportAbility
Prankster+Def
42 +9Spe
91Smeargle
NORMAL
Role
Bulky SupportAbility
Owntempo+Def
35 +8Spe
75Qwilfish
WATER POISON
Role
Bulky SupportAbility
Intimidate+Def
85 +13Spe
85Cobalion
STEEL FIGHTING
Role
Bulky SupportAbility
Justified+Def
129 +18Spe
108Sableye
DARK GHOST
Role
Bulky SupportAbility
Prankster+Def
75 +12Spe
50Ditto
NORMAL
Role
Bulky SupportAbility
Imposter+Def
48 +10Spe
48Dachsbun
FAIRY
Role
Bulky SupportAbility
Wellbakedbody+Def
115 +16Spe
95Swalot
POISON
Role
Bulky SupportAbility
Stickyhold+Def
83 +13Spe
55Dhelmise
GHOST GRASS
Role
Bulky SupportAbility
Steelworker+Def
100 +15Spe
40Nosepass
ROCK
Role
Bulky SupportAbility
Sturdy+Def
135 +18Spe
30Hippopotas
GROUND
Role
Bulky SupportAbility
Sand Stream+Def
78 +13Spe
32Steelix
STEEL GROUND
Role
Bulky SupportAbility
Rockhead+Def
200 +25Spe
30Runerigus
GROUND GHOST
Role
Bulky SupportAbility
Wanderingspirit+Def
145 +19Spe
30Klawf
ROCK
Role
Bulky SupportAbility
Regenerator+Def
115 +16Spe
75Pineco
BUG
Role
Bulky SupportAbility
Sturdy+Def
90 +14Spe
15Aggron
STEEL ROCK
Role
Bulky SupportAbility
Rockhead+Def
180 +23Spe
50Toxicroak
POISON FIGHTING
Role
Bulky SupportAbility
Dryskin+Def
65 +11Spe
85Miltank
NORMAL
Role
Bulky SupportAbility
Thickfat+Def
105 +15Spe
100Trevenant
GHOST GRASS
Role
Bulky SupportAbility
Harvest+Def
76 +12Spe
56Wooper
WATER GROUND
Role
Bulky SupportAbility
Unaware+Def
45 +9Spe
15Orbeetle
BUG PSYCHIC
Role
Bulky SupportAbility
Frisk+Def
110 +16Spe
90Tinkatuff
FAIRY STEEL
Role
Bulky SupportAbility
Mold Breaker+Def
55 +10Spe
78Pincurchin
ELECTRIC
Role
Bulky SupportAbility
Electric Surge+Def
95 +14Spe
15Dewgong
WATER ICE
Role
Bulky SupportAbility
Thickfat+Def
80 +13Spe
70Swellow
NORMAL
Role
Bulky SupportAbility
Guts+Def
60 +11Spe
125Wobbuffet
PSYCHIC
Role
Bulky SupportAbility
Shadowtag+Def
58 +11Spe
33Cradily
ROCK GRASS
Role
Bulky SupportAbility
Stormdrain+Def
97 +14Spe
43Dragonair
DRAGON
Role
Bulky SupportAbility
Shedskin+Def
65 +11Spe
70Crustle
BUG ROCK
Role
Bulky SupportAbility
Sturdy+Def
125 +17Spe
45Gourgeist
GHOST GRASS
Role
Bulky SupportAbility
Frisk+Def
122 +17Spe
84Druddigon
DRAGON
Role
Bulky SupportAbility
Rough Skin+Def
90 +14Spe
48Falinks
FIGHTING
Role
Bulky SupportAbility
Defiant+Def
100 +15Spe
75Hakamo-o
DRAGON FIGHTING
Role
Bulky SupportAbility
Bulletproof+Def
90 +14Spe
65Fidough
FAIRY
Role
Bulky SupportAbility
Owntempo+Def
70 +12Spe
65+10%Defense
-10%Sp. Attack
Flavor Preference
Likes Sour, dislikes Dry
Competitive Role
Physical walls that rely on physical or status moves.
Impish vs Bold
Choose Impish
+Defense / -Sp. Attack
- Pokemon that need to check physical threats (use +Def)
- Pokemon that need to check special threats (use +SpD)
- Walls and tanks that rarely attack
Choose Bold
+Defense / -Attack
- Defensive Pokemon that still need attacking power
- Pokemon that run both physical and special moves
How to Get
SynchronizeLead with a Impish Pokemon that has the Synchronize ability. Wild Pokemon will match its nature. (Gen 3+)
BreedingGive the parent with Impish nature an Everstone. The offspring will inherit it. (100% since Gen 5)
Nature MintUse an Impish Mint to change stat effects to Impish. The original nature name stays but stats change. (Gen 8+)
Other +Defense Natures
What does the Impish nature do in Pokemon?
It's a +10% Defense, -10% Sp. Attack nature. The 10% multiplier applies after base stats and EVs, so the actual point difference grows as stats get higher. Pokemon with Impish nature prefer Sour flavor and dislike Dry.
What are the best Impish nature Pokemon?
Ho-Oh, Ting-Lu, Giratina, and Mudbray are among the strongest Impish picks. What they share is a reliance on Defense and little need for Sp. Attack. Check the tier list for current rankings.
Is Impish a good nature for competitive Pokemon?
Yes. It fills a solid niche for defensive builds. You'll see Impish on dedicated Defense-focused builds across most tiers and formats.
How do I get an Impish nature Pokemon?
Three options: (1) Synchronize lead forces wild Pokemon to match your lead's nature. (2) Everstone breeding passes the nature 100% of the time since Gen 5. (3) an Impish Mint changes the stat effects after the fact. Mints don't change the nature name, just the stat modifiers.
Should I use Impish or Bold?
It depends on what your team needs. Impish is the physical defense utility option. Bold is the special defense utility option. Most of the time, your Pokemon's moveset and role make the decision obvious.