Multislap is a move that slaps the opponent. All Pokemon with actual finger hands can use this move, and the move's power is the Pokemon's level times the number of fingers divided by the opponent's level. So if a level 90 Mr. Mime used Multislap on a Level 5 Nidoran Male, the damage would be 90 points, which would knock the Nidoran Male out. This is why Pokemon with no fingers cannot use the move, since it would have 0 points damage.
ANY POKEMON WITH FINGERS CAN USE THIS MOVE.