Not that he wasn't also a cliche, but I think Quicksilver came the closest to having nuance to his character. Unlike Magneto's complete sociopathy, Raven's refusal to think about the political impacts of any of her planned politician-murderings (maybe she should, like, actually go to college), or Trask's completely opaque reasoning for why he needs to invent unstoppable racist death robots, Quicksilver's moral landscape is refreshingly gray. He does good if it's fun, and he steals shit and messes with people because he finds that fun, but he's not by that token incapable of empathy.
That being said, I'm pretty sure the X-men didn't call him in because Quicksilver is a great match for Magneto on his own and Evan Peters isn't an important enough actor to actually be involved in that fight. Same reason why Ellen Page's character needs to stoically endure pain (small favors though: I'm grateful she didn't get many lines. Her delivery is still atrocious), or why we get an extended scene of Hugh Jackman standing around naked.
For good measure, a couple plot holes not mentioned in the review:
1) They have a serum that can cure goddamn spinal paralysis, and the guy who invented it is still alive 50 years later. Why hasn't anyone done any work to improve it such that the serum lets Xavier walk but doesn't turn off his powers? I hope at the very least there's some, "Holy shit, there's this awesome serum that helps paraplegics walk! Nobel prize time, Hank McCoy!"
2) At the end of the movie, when Magneto's helmet is off, Charles can clearly control both his actions and his powers. The helmet is also right there, in plain view of both of them. Why doesn't Xavier have Magneto smash it to bits before he lets him go? There is literally no reason for Xavier to do anything other than destroy it at this point. Sure, Magneto can probably figure out a way to make a new one, but why not at least make it difficult for him?
3) Somebody with super speed and reflexes should be good at Pong. Quicksilver shouldn't have any points at all on the scoreboard, or at the very least he should have broken the joystick within two seconds of starting to play if even tapping somebody's face when he's at super speed knocks that person the fuck out.
4) This isn't original to this movie, but still bothers me: does Raven naturally not have nipples or a vagina, or does her 'natural form' come with a removable seamless bikini? I'm seriously not 100% sure how she's supposed to have kids unless they come out of her mouth, or if she can even have sex when she's in blue girl mode.