Serious keeps every stat at 1x. No boost, no drop. That might sound safe, but you're giving up a free 10% in the stat that matters most. Nature Mints (Gen 8+) make it easy to fix. Don't queue into competitive with Serious. Nature Mints are cheap in Legends: Z-A.

Serious is a neutral nature with no stat change. For speed pokemon, use Jolly or Timid instead.
#PokemonNatureTierRoleAbilitySpe
1
Greninja
Greninja
WATERDARK
TimidSSpecial AttackerBattlebond122
2
Gholdengo
Gholdengo
STEELGHOST
TimidSUtilityGoodasgold84
3
Excadrill
Excadrill
GROUNDSTEEL
JollySPhysical AttackerMold Breaker88
4
Garchomp
Garchomp
DRAGONGROUND
JollySPhysical AttackerRough Skin102
5
Latios
Latios
DRAGONPSYCHIC
TimidSSpecial AttackerLevitate110
6
Kyogre
Kyogre
WATER
TimidSSpecial Revenge KillerDrizzle90
7
Tyranitar
Tyranitar
ROCKDARK
JollyAPhysical AttackerSand Stream61
8
Gengar
Gengar
GHOSTPOISON
TimidASpecial AttackerLevitate110
9
Starmie
Starmie
WATERPSYCHIC
TimidASpecial AttackerNatural Cure115
10
Heatran
Heatran
FIRESTEEL
TimidASpecial AttackerFlashfire77
11
Glimmet
Glimmet
ROCKPOISON
TimidAUtilityToxicdebris60
12
Mimikyu
Mimikyu
GHOSTFAIRY
JollyAPhysical AttackerDisguise96
13
Jolteon
Jolteon
ELECTRIC
TimidASpecial AttackerVoltabsorb130
14
Espeon
Espeon
PSYCHIC
TimidASpecial AttackerMagic Bounce110
15
Annihilape
Annihilape
FIGHTINGGHOST
JollyAUtilityDefiant90
16
Chandelure
Chandelure
GHOSTFIRE
TimidASpecial AttackerFlashfire80
Greninja
Greninja
WATER DARK
S
Nature
Timid
Role
Special Attacker
Ability
Battlebond
Spe
122
Gholdengo
Gholdengo
STEEL GHOST
S
Nature
Timid
Role
Utility
Ability
Goodasgold
Spe
84
Excadrill
Excadrill
GROUND STEEL
S
Nature
Jolly
Role
Physical Attacker
Ability
Mold Breaker
Spe
88
Garchomp
Garchomp
DRAGON GROUND
S
Nature
Jolly
Role
Physical Attacker
Ability
Rough Skin
Spe
102
Latios
Latios
DRAGON PSYCHIC
S
Nature
Timid
Role
Special Attacker
Ability
Levitate
Spe
110
Kyogre
Kyogre
WATER
S
Nature
Timid
Role
Special Revenge Killer
Ability
Drizzle
Spe
90
Tyranitar
Tyranitar
ROCK DARK
A
Nature
Jolly
Role
Physical Attacker
Ability
Sand Stream
Spe
61
Gengar
Gengar
GHOST POISON
A
Nature
Timid
Role
Special Attacker
Ability
Levitate
Spe
110
Starmie
Starmie
WATER PSYCHIC
A
Nature
Timid
Role
Special Attacker
Ability
Natural Cure
Spe
115
Heatran
Heatran
FIRE STEEL
A
Nature
Timid
Role
Special Attacker
Ability
Flashfire
Spe
77
Glimmet
Glimmet
ROCK POISON
A
Nature
Timid
Role
Utility
Ability
Toxicdebris
Spe
60
Mimikyu
Mimikyu
GHOST FAIRY
A
Nature
Jolly
Role
Physical Attacker
Ability
Disguise
Spe
96
Jolteon
Jolteon
ELECTRIC
A
Nature
Timid
Role
Special Attacker
Ability
Voltabsorb
Spe
130
Espeon
Espeon
PSYCHIC
A
Nature
Timid
Role
Special Attacker
Ability
Magic Bounce
Spe
110
Annihilape
Annihilape
FIGHTING GHOST
A
Nature
Jolly
Role
Utility
Ability
Defiant
Spe
90
Chandelure
Chandelure
GHOST FIRE
A
Nature
Timid
Role
Special Attacker
Ability
Flashfire
Spe
80
Serious is a neutral nature — no stat is increased or decreased.
Competitive Role
No competitive advantage. A stat-boosting nature is almost always preferred.
How to Get
SynchronizeLead with a Serious Pokemon that has the Synchronize ability. Wild Pokemon will match its nature. (Gen 3+)
BreedingGive the parent with Serious nature an Everstone. The offspring will inherit it. (100% since Gen 5)
Nature MintUse a Serious Mint to change stat effects to Serious. The original nature name stays but stats change. (Gen 8+)
What does the Serious nature do in Pokemon?
Nothing, basically. Serious doesn't change any stat. There's no boost and no penalty. Your Pokemon keeps its base stat spread exactly as-is.
Is Serious nature good?
There's no competitive reason to keep Serious. A 10% stat boost from any other nature is free power you're leaving on the table. Nature Mints (Gen 8+) let you change it without breeding.
How do I get a Serious nature Pokemon?
Catch a Pokemon and check. There's a 4% chance of any specific nature, including Serious. Synchronize ability matches the lead Pokemon's nature to wild encounters (Gen 3+). Everstone passes a parent's nature during breeding.
When should you use a neutral nature?
Almost never. The only edge case is a Pokemon that uses physical moves, special moves, and needs every defensive stat and Speed. That Pokemon doesn't really exist in competitive. Even mixed attackers prefer Naive, Hasty, or another nature that at least boosts Speed.