Eelevate is an ability introduced in generation 9.
No Pokémon has this ability in the current games.
Official effect
The Pokémon floats off the ground, making it immune to Ground-type moves, as well as the Spikes, Toxic Spikes, and Sticky Web statuses. When the Pokémon knocks out a target with an attack, its highest stat is boosted by 1 stage.