Was Nidoking ever this tiny? In short, no, but it was never a spriteswap of Kung Fu Man either. You'll find no Pokémon-related moveset here, only attacks that fail to hit the opponent despite having hitboxes on them.
Nidoking is a spriteswap of Kung Fu Man, much like Hugespongebob98's other characters. The hitboxes remain intact for the most part, though there are some animations where the hitboxes were resized to match Nidoking's size, but only for a frame or two.