What it does
STAB — Same Type Attack Bonus — normally multiplies damage by 1.5 when you use a move that matches your Pokémon's type. Adaptability raises that multiplier to 2.0. Same conditions, 33% more damage on every same-type move.
Putting that in concrete terms: a move with 80 base power hits at effective power 120 under normal STAB, or 160 under Adaptability. A 100-power move goes from effective 150 to effective 200. That gap matters at threshold points — matchups where the opponent's Pokémon would survive one hit at 1.5× but gets KO'd at 2.0×.
Adaptability only affects moves that match one of your types. Off-type moves are unchanged.
Who runs it
Basculegion is the main Adaptability user in Champions (86%). Water/Ghost typing means two completely different move lines both get the 2.0× boost. Wave Crash — a Water-type physical move with 120 base power — hits at effective physical power 240 under Adaptability. Ghost-type moves like Shadow Ball or Hex hit Psychic and Ghost-type targets at the same elevated rate.
Water and Ghost coverage complement each other: Water hits Fire, Rock, and Ground; Ghost hits Psychic and Ghost both ways. With 2.0× behind both lines, almost every move Basculegion throws is a serious threat.
How to use it
Build both coverage lines with strong moves — Wave Crash (or Liquidation) on the Water side, a Ghost-type move for the other. The whole point is having two high-multiplier move types available.
Wave Crash has recoil (the user takes 1/3 of damage dealt), but under 2.0× Adaptability the trade-off is usually worth it: you deal enough damage that recoil is an acceptable cost. If you need more longevity, Liquidation drops some power but removes recoil.
In doubles, the Water + Ghost threat from a single Pokémon forces the opponent to think carefully at team preview. Covering Ghost-weak Psychic and Ghost types on the same set as Water pressure is unusual coverage for one slot.
Tips & strategy
Adaptability + Choice Band or Life Orb is standard. Adaptability has already maximized the type multiplier; adding a damage item on top pushes the output into a range that normally requires a Swords Dance.
Adaptability doesn't override type immunities. Ghost moves have zero effect on Normal and Fighting types. Water moves hit Grass and Dragon at 0.5×. A 2.0× STAB multiplier applied to 0× is still zero. Know which targets each move line doesn't reach.
Build your team to cover those gaps — specifically Normal-types that wall Ghost moves, and Grass-types that resist Water. Basculegion hits hard but can be blanked if the opponent has the right answers.