If a comeback were possible, I would definitely want Bigweed and Lil Seaweed written out... or at least downplayed. I'd also want Dimmy back, because the last two seasons weren't the same without him. If they had kept Dimmy in the first place and not added the Sea Urchins as the main villains, then the show would've gone well into the early 90's (around '90 or '91-'92). Keeping Corky and Jojo around would also be a huge plus, and they could add a few more new characters as well.

I'd definitely want the writing and animation to be similar (and maybe slightly more updated, but not entirely flash) to that of the first two seasons. And I would really like it if they chose to focus more on the relationship between Allstar and Casey, but not go overboard, as well as add on to the Dimmy and Daffney relationship. Obviously, the latter was nonexistant in the final seasons, and the writers chose not to focus on Allstar and Casey for some odd reason (Snorkerella - and Snork Ahoy, as a matter of fact - thoroughly made it clear that they no longer liked each other).