Splash is a non-damaging Normal-type move introduced in Generation I.
Prior to Generation II, it was the signature move of Magikarp. It
has no effect whatsoever in the main series games.
In Pokémon mystery dungeon
> The user will move to a random different tile one ratio away. The user
> will inflict 5 damage to itself and the opponent if the move comes in
> contact with another Pokémon
In the main Pokémon games splash will never ever do any damage, sorry to disappoint you