USUM expands the Alola Pokedex over Sun and Moon. More Pokemon are available earlier, new Ultra Beasts join the roster, and Ultra Warp Ride opens up legendaries from every past generation. The late game is harder too. Ultra Necrozma will sweep your team if you're not ready. Same Trial system, bigger Pokedex.
Showing all 787 Pokemon obtainable in Ultrasun Ultramoon, including post-game content and trading.
How the USUM Pokedex expanded from Sun & Moon
USUM boosts the Alola dex from 302 to 403 Pokemon. Over 100 species are available that weren't in the originals.
Ultra Wormhole travel is the standout postgame feature. Ride Solgaleo or Lunala through wormholes and you can encounter every non-event legendary from past generations. The farther you travel, the rarer the finds. Island Scan (QR codes) adds more variety on a weekly rotation. With Pokemon Bank, the full 807 is reachable.
Klang
Klinklang
Tynamo
Eelektrik
Eelektross
Litwick
Lampent
Chandelure
Axew
Fraxure
Haxorus
Cubchoo
Beartic
Cryogonal
Shelmet
Accelgor
Stunfisk
Bouffalant
Heatmor
Durant
Deino
Zweilous
Hydreigon
Cobalion
Terrakion
Virizion
Tornadus
Thundurus
Reshiram
Zekrom
Landorus
Kyurem
Chespin
Quilladin
Chesnaught
Fennekin
Braixen
Delphox
Froakie
Frogadier
Greninja
Bunnelby
Diggersby
Scatterbug
Spewpa
Vivillon
Skiddo
Gogoat
807 total, five more than Sun and Moon. The new additions are Ultra Beasts: Poipole, Naganadel, Stakataka, Blacephalon, and Zeraora. The Alola dex is slightly expanded with more encounter options early.
The story diverges around the midpoint. Necrozma absorbs the box legendary to become Ultra Necrozma, one of the hardest boss fights in any Pokemon game. Ultra Warp Ride lets you catch legendaries from every past generation. New Ultra Beasts, more early encounters, and the Mantine Surf minigame are added.
Ultra Necrozma has 167 Sp. Atk, 97 Speed, and gets a stat-boosting aura on top of that. It will sweep most teams. Common strategies: Zoroark's Illusion to bait a Fighting-type move, Toxic stalling, or a Focus Sash Pokemon with a super effective hit. It's level 60 and the biggest difficulty spike in the series.
A minigame where you fly through Ultra Space on Solgaleo or Lunala. Different colored wormholes lead to different Pokemon. Legendary Pokemon from past generations (Mewtwo, Ho-Oh, Groudon, etc.) appear in the furthest wormholes. It's the main way to catch non-Alolan legendaries without transferring from older games.
Still Gen 7, 3DS, 2017. USUM is the enhanced take on Alola. Same Trial system, but the story diverges around the midpoint into Ultra Space content. More Pokemon available earlier, new Ultra Beasts, and a harder endgame stretch.
Same three starters as Sun and Moon. Litten's Incineroar is still the most practical for the story since Intimidate neuters Totem Pokemon. But team building matters more in USUM because Ultra Necrozma demands a specific answer on your squad.
- Gen IY
Yellow151 Pokemon - Gen IRB

Red & Blue151 Pokemon - Gen IIGS

Gold & Silver251 Pokemon - Gen IIC
Crystal251 Pokemon - Gen IIIRS

Ruby & Sapphire202 Pokemon - Gen IIIFRLG

FireRed & LeafGreen151 Pokemon - Gen IIIE
Emerald202 Pokemon - Gen IVPt
Platinum210 Pokemon - Gen IVHGSS

HeartGold & SoulSilver256 Pokemon - Gen IVDP

Diamond & Pearl151 Pokemon - Gen VBW

Black & White156 Pokemon - Gen VB2W2

Black 2 & White 2301 Pokemon - Gen VIXY

X & Y457 Pokemon - Gen VIORAS

Omega Ruby & Alpha Sapphire211 Pokemon - Gen VIIUSUM

Ultra Sun & Ultra Moon403 Pokemon - Gen VIISM

Sun & Moon302 Pokemon - Gen VIILGPE

Let's Go Pikachu & Eevee153 Pokemon - Gen VIIISwSh

Sword & Shield400 Pokemon - Gen VIIIPLA
Legends: Arceus242 Pokemon - Gen VIIIBDSP

Brilliant Diamond & Shining Pearl151 Pokemon - Gen IXSV

Scarlet & Violet400 Pokemon - Gen IXLZA
Legends: Z-A364 Pokemon - Gen XWW

Winds & Waves51 Pokemon