You gotta stop with the "this character isn't a protagonist so they shouldn't have gotten in" thing. That's the sort of roster Ludosity wanted to avoid.
Being a bit of a hypocrite, huh?
She may be a fan favorite, but you can't deny it's straight up weird not having all four turtles when they're literally always all in or none in every other crossover. The show's about all four, they're all equal.
I also don't have any problems with Nigel, Helga, Shredder, PTM, or Reptar. It's literally just Hugh and April I genuinely do not like on the roster. And that's even considering the fact that I ****ing despise The Legend of Korra, especially Korra as a character.
And seriously, are you actually gonna believe they added her because of "oh she'd have an interesting moveset!" It's a load of crock. Have you seen how many boys AND girls had their sexual awakening to April O'Niel back in the 80s? To think that nobody that fought for her because of that reason is silly. Hell, her sex appeal is the primary reason she IS so damn popular.
She's also obnoxious to fight. Even if I didn't despise her being on the roster for taking away Raph's shot, I'd hate her for how atrocious she was at launch. Brawl Meta Knight eat your heart out. And she's still a pain in the ass.
I never said that I liked the way Ludosity went about with the roster. It being predictable isn't necessarily a bad thing, and I don't think they shouldn't have some crazy picks - I think the roster is generally pretty good - but I don't believe in the philosophy of passing over the main protagonist because "ermahgerd SOOOO PREDICTABLEEEEEEEEE"
You're supposed to generally like main protagonists, and yes, sometimes they aren't fit for this kind of game, but if you get for example the Mario IP, are you seriously gonna say "I'm gonna put in Birdo before Mario because everyone would see Mario coming!" No, you wouldn't. That's prioritizing shock value over actual substance, and that's April and Hugh to me.
If you like April and Hugh, more power to you. If you want this roster to have these weird picks, that's your prerogative. But my opinion is just as valid as yours is. I want to see characters I actually give a damn about, rather than just pulling names out of a hat. I have nostalgia for Jimbo, Donnie, and Raph, not their random secondary characters, and I'd rather see them over someone the devs thought would be "lol more interesting." And to prove I'm not blatantly so "protagonist biased," there are literally dozens of Nick protags I wouldn't want in this game under any circumstances, even from shows I like - for example, Vendetta from Making Fiends. I liked that show a lot. But there's also dozens of characters, including side characters, that I think deserve a shot before her.