Damaging move, causes recoil
Struggle is a damage-dealing move. It is a move that no Pokémon naturally learns but every Pokémon can use if none of their other moves are usable, usually due to a lack of PP. When used, the user is hit with recoil equivalent to ¼ of their max HP.
All Pokémon can use Struggle when they cannot use any other moves, such as by them all having 0 PP, or if they are all incapacitated through any of Disable, Taunt, Torment, Imprison, Heal Block, Cursed Body or Choice items. Also, some moves cannot be selected unless specific conditions are met, so can also cause the Pokémon to Struggle if they are the only moves with PP.