Idea that came to me right as I got up this more, so blame it on being sleep-addled. Mojo shows up, but has set his sights on the Inhumans instead of the X-Men. He figures the mutants have gone stale and bringing in some new attractions will give him a leg up in that ratings-driven struggle for supremacy. Except no matter what angles he tries to introduce, he can't get people interested. He loses control and comes crawling back to the X-Men, trying to finagle them into helping him make a comeback.
OK, it's a lazy gag. But I do like the idea of having Mojo torment/annoy some other heroes. I don't dislike the character as much as some X-fans I know do. I think as long as you don't overuse him, he can be a fun antagonist once in awhile. There's nothing about him that makes him strictly an opponent for the X-Men. He's typically a would-be dictator, albeit one who abuses people other than the ones he's ruling. He doesn't have to abuse his audience, just keep them enraptured with what he puts on the screen. He can mess with any hero for that, try to drag them through hell, put them into cheap dramatics, confront them with infinite cheap knock-offs of themselves. just so long as he keeps people's eyes glued to what he's selling.
Although if you wanted something more terrifying, they could go back towards his original personality in Ann Nocenti and Art Adams' Longshot mini-series. He was more like a particularly vicious child. Focused only on his own desires and wants. That bloated yellow form, skittering around on mechanical bug legs, screeching in what is almost certainly a hideous voice (to say nothing of the smell). Everything near him sickens and dies, to his utter lack of concern. What he doesn't kill (if they're lucky), he'll have torn apart and changed to suit his purposes. That's a fairly decent threat for a hero or heroes to contend with, especially if they or their loved ones are drawn onto his turf.