You want a random ass rep in Smash? A Sega One?
HEAR ME OUT.
Book from Wonder Boy: The Dragon's Trap.
The gimmick? He would wield a specific sword from the game, the Tasmanian Sword, which allows him to transform into other creatures on a whim. (as opposed to beign stuck in that form as he usually is in the actual game)
Not a Transformation character like PT, but rather similar to Corrin or Pac-Man's Side Special and Dash Attack. In certain moves he transforms to attack,. Smash Attacks have him turn into LION-MAN, the strongest form of all perfect for dealing damage. For his Recovery and Aerials, he turns into HAWK-MAN, allowing him to fly freely. For his Dash, he turns into MOUSE-MAN, a quick and small but powerful rodent that can climb walls. For his Up, Side and Down Specials he turns into LIZARD-MAN, allowing him to breath Fire.
For PIRANHA-MAN......................i got no clue. Swimming animation i guess? HU-MAN takes one the tilts, Jab, Grab, get up attacks with his trusty sword and gadgets plus all other animations.
In Wonder Boy TDT, all forms except Lizard used the Sword and Shield combo, but for Smash we could take some liberty. The Lion-Man instead would mawl you or let out a big roar that acts similar to Shovel Knight's Horn. The Hawk-Man would instead use his legs and wings to attack, etc.