Story-related mission and cannot be missed.
For the boss battle, you'll want allies with knockback since that's the only way to really damage the boss. SuperCraig, Mysterion, and Captain Diabetes are all good choices (especially Mysterionsince he can't really die). Not a terribly hard battle but takes a little bit of time if you can't get the right lineup. I found equipping freeze powers (Elementalist's super for the New Kid) helps to freeze enemies in place so you can do your thing.