Why do people ask this every week? Goku already has ENOUGH transformations! GT has almost none cool attacks or good new charackters... Baby? He's Vegeta with a Freza Deathball... Super 17? He's like A18 just that he's also gay or something... and absorbing attacks? No one can balance that. This General? Guess no one would play him. Any of the dragons? Omg... was there a lamer reason in finding some new uber strong villians ever? None of them has really good techniques.
Instead people should wonder why they dont add Dabura into the game. He has also a mystic Transformation and a lot of unique attacks and also a sword, so a counter part to Trunks.