Hm, I don't really see how battle damage (i.e having seven shades of brown stuff kicked out of you) constitutes a trans, but he does have one unique attack,
the one that he throws at Frieza in space (but the Deathball eats it) it could well be a genball but considering the ki surrounds his hand rather than being a ball (like the start of Yamcha's Spirit Ball) and the fact that it's lobbed rather than fired. It's pretty big.
Not that i'm for this idea, but why can't TV Special characters be in ESF? I can understand movie characters as they're seperate from the timeline, and GT stuff because it isn't DBZ, but the TV Specials (Bardock, World Of Dragonball, History of Trunks) are all directly related to the DBZ series timeline like the Sagas are.