>>49274782>>49275035It's not a real creature you mongoloid, it's a roid-raging mutant because fuck you, that's why. It lost its tail because that makes it ambiguous or mysterious, something that early gen designs clearly championed.
If you want an explanation, then the massive amount of physical training it endured becoming swole stunted its development and it thus traded its potential change into a frog's form for raw strength and bulk.
Thank christ most older Pokémon weren't designed by the creatively bankrupt like you and didn't turn out to be literal animals with nothing unique or interesting about them to differentiate themselves from the real world.
