Effect
Vital Spirit prevents the ability-bearer from falling asleep, which also prevents the use of the move Rest.
Outside of battle
If a Pokémon with Vital Spirit is the leading party Pokémon, wild Pokémon are 50% more likely to be higher level.
The Pokémon is full of vitality, and that prevents it from falling asleep.
Vital Spirit prevents the ability-bearer from falling asleep, which also prevents the use of the move Rest.
If a Pokémon with Vital Spirit is the leading party Pokémon, wild Pokémon are 50% more likely to be higher level.