I feel that if I was in charge of a Shredder's Revenge esque Simpsons Arcade sequel, I'd have the 3 extra playable characters be Flanders, Krusty, and Maggie (possibly in a pram, even though she's never been in one in canon to my knowledge). Itchy and Scratchy as another character if there's enough dev time for a fourth. I'd personally make Sideshow Bob the main villain, but Kang & Kodos or Hank Scorpio could work too (and either way Hank would be a boss at least, though I feel Kang & Kodos would be final boss or bust, maybe Bob appears to be the main villain but then Kang & Kodos usurp him at the last minute)