I know you started this long before I made this topic, but it almost sounds like you're getting ahead of yourself, Will...
I liked the SMBSS as a kid, but I don't know about this idea. It almost seems like this idea is too dependent on people being fans of the show. Do we have enough fans here? Would gamers these days be enough of fans to remember the cool episodes? Doing something based on Captain N seems like a slightly better idea IMO, but probably not by much...
Though it does give me an idea. How about a NES or Super NES-based Super Smash Bros.? It would be far less work and a fair bit of fun to create 40some arenas, even if they were, like, 2 x 2 screens each... It would allow for some creativity, yet be easier as things are meant to look like they were adapted from other games, be more flexible in allowing other people to join in or drop out during the course of working on it, and it wouldn't be a disaster if it weren't completely done (more like if we didn't have the ideal number of stages) by the end of it... (With the timing, maybe this would've been a better joke for this year...)
(And if we wanted it to be current, we could try for a DS-based Super Smash Bros.! Though people might expect it to have 3D N64-like graphics...)
You'd almost need to have each arena looked over by everyone else, though. Quality control might be necessary, as it might be too easy. Maybe we'd throw in some kind of story/adventure mode if we wanted some challenge...
In an ideal situation, (that is, if we had the time, resources, but mostly dedication) I still really like the Metroid Dread idea, but in terms of feasibility, some kind of 2D Smash Bros. would work better.
But what do you guys think?