Generation Iii
Shadow Tag
Prevents the foe’s escape.
Detailed Effect
While this Pokémon is in battle, opposing Pokémon cannot flee or switch out. Other Pokémon with this ability are unaffected. Pokémon with Run Away can still flee. Pokémon can still switch out with the use of a move or item.
Pokémon With Shadow Tag
6 canonical Pokémon forms can have this Ability.

Wobbuffet
Wynaut
Mega Gengar
Gothita
Gothorita
Gothitelle