(I know most of these probably won't happen, but I'm listing anyway).
Rudy Tabootie, Snap, Scrawl, Skuller, Tak, Lok, El Tigre, Jenny Wakeman, Mr. Blik, Waffle, Gordon, Dora (She has plenty of tools in her backpack and would make a great moveset).
All I really hope for is no one from Mr. Meaty, they already haunt my dreams, imagine them in HD with a probably low budget, no one should ever have to see that
I also hope we get the turtles from Rise instead of 2012