Awesome / Ben 10/Generator Rex: Heroes United
Here's a list of the Ben 10 Aliens that appear on screen (most are just cameos): Heatblast, Wildmutt, Diamondhead, Stinkfly, Upgrade, Rip Jaws, Way Big, Four Arms, Rath, Echo Echo, Chromastone, AmpFibian, XLR8, Cannonbolt, Spidermonkey, Goop, Jet Ray, Big Chill, Shocksquatch and Brainstorm. They got the band back together.
After Six gets injured, Ben is arrested and taken to custody in Providence's headquarters. While they are trying to heal Six and figure out what's going on, he offers to help, and Rex reacts by pointing out he is under house arrest... only for Ben to reveal with a grin he could escape whenever he wanted and was just staying to see if he could help. Cue him turning into Big Chill and casually walking out of his cell.
Upgrade- enhanced Rex. That is all.
Rex: What happens when the best you can do just... isn't enough?
Rex: Weren't you listening? Alpha has the Omega!
Ben: I'm not talking about a nanite.
(Ben turns into Upgrade, and merges with Rex)
Ben!Upgrade: Build something.
Rex: ( uses his giant fists, resulting in twice as tall fists with spikes on them) Sweet! So what's the plan?
Ben!Upgrade: You build stuff, I make it better. Fight, fight, fight. We win.
The fight between Ben and Rex.
Particularly, Rex vs Humungousaur.
Alpha, and his alien EVO transformations are pretty much badass personified.