(Sorry in advance for getting so technical.)
Ahem.
_Technically_ (see? technical) Brolli's what you'd call a "Legendary Super Saiyan." This means that he kicks way more AHEM! than an USSJ. Plus, he's not only far, far more powerful than an USSJ (I think he even outclasses SSJ2, but don't quote me on that), but he's also physically huge. USSJs really aren't all that different than other forms, except for the ridiculously bulky musculature. Brolli is not only a huge slab o' meat, he's also really, REALLY tall... Possibly over 8 feet. Trunks is only what, 5'10"?
And, to make this relevant to the actual game, I'd have to add that Brolli is not a good idea, except possibly for a special game scenario. He's just so absurdly powerful that he'd turn anyone else into marinara sauce on the ground.
USSJ Trunks I don't have a problem with, because (as we all know) he's pretty strong, but h3lla slow. Also, I like USSJ Trunks because it just goes to show you just 'cuz your momma's a genius don't mean you're not a friggin moron.
*Shrug* that's about all I have to say about that. You guys alseep yet?