Ability · Gen 3 · 3 Pokémon
Arena Trap
Prevents opposing Pokemon from choosing to switch out unless they are airborne.
Prevents opposing Pokemon from choosing to switch out unless they are airborne, are holding a Shed Shell, or are a Ghost type.
Arena Trap was introduced in Generation 3. 3 Pokémon and forms can have it.
Diglett
Dugtrio
TrapinchArena Trap FAQ
What does Arena Trap do?
Prevents opposing Pokemon from choosing to switch out unless they are airborne, are holding a Shed Shell, or are a Ghost type.
Which Pokémon have Arena Trap?
3 Pokémon and forms can have Arena Trap: Diglett, Dugtrio and Trapinch.
Effect text from Pokémon Showdown (MIT); which Pokémon have it from Showdown's Pokédex, cross-checked against PokéAPI. Unofficial fan site.