If Cranky Kong was playable, he should play like this:
He is an old man but very nimble and acrobatic, being able to swing his cane around and jump quite high.
His neutral B is cane bounce. When used on the ground he jabs at the ground with his cane launching him up and hurting anyone he standing next to him. When used in the air, he strikes downward like a pogo stick, and he can continue to bounce like this around the stage each time he presses B.
His down-B drops a fire barrel from the DK Arcade game. Like Pac-Man's Fire Hydrant, it can be dropped on top of people off stage and such. Once it lands, it can spit out fireballs, and if it gets hit it explodes.
His side-B throws barrels, which pop when they hit people, but otherwise roll on the ground and off the side of the stage.
His Up-B would either be the DK Arcade Spring, or Squawks the parrot (which I think should be in his moveset somewhere either way).
His Final Smash would have him pull out one of his patented potions and drink it. After drinking the potion, he transforms into Classic 8-bit Donkey Kong. While in this state, anyone he touches gets launched, and he can throw stronger barrels more frequently than usual.