Rest (ねむる, Sleep) is a non-damaging Psychic-type move introduced in the first generation.
When a Pokemon uses rest, it puts itself to sleep and heals every turn it's in sleep.
By leveling up
Super Smash Bros. series
In all five Super Smash Bros. games, including Super Smash Bros., Super Smash Bros. Melee, Super Smash Bros. Brawl, Super Smash Bros. for 3DS, and Super Smash Bros. for Wii U, the playable character Jigglypuff can perform Rest. To the unobservant eye the move appears to be pointless as it causes Jigglypuff to fall asleep and become vulnerable for a short time. However, if performed correctly it can inflict massive damage and knockback on the opponent and send them soaring off of the stage.