Seeing my Little Colosseum mentioned, I couldn’t resist making this post! >.> Without bias, Little Colosseum is a community runned tier with an active player base. It recently gotten a format and ladder for main and tours. And doesn't have a super overlapping community wich is probably a good thing when it comes to 12 slot tournament. I do believe its a competitve format but ofcourse thats just my opinion. (adv should be locked in imo)
As a manager who likes to have an understanding of what my players are doing and their preferences, and to be able to help wherever needed, I absolutely 100% will never sign up to manage if this tier is included. This would be horrible for literally every manager that isn't Quinn, as yeah, while it might have a small and good community being dedicated to it, none of these are (to my knowledge) potential managers. The main issue here tho is that while across DLC/LCUU/ADVLC etc, while there are obvious differences between the tier, all mons have the same stats, abilities and moves (with additions in later gens obviously as well as gen specific removals but not to an alarming extent). This means even for tiers where a manager and other teammates might want to do what they can to help, most mons are gonna play similarly between gens, and have similar potential, with minor deviations based on meta etc. Yes there are differences etc, like Gastly being bulky in gen 5 and purely offensive gen 7, but the core mon has the same stats and moves with just a few minor differences, and the main differences in how it functions in the metagame is based on the surrounding metagame and not the mon itself.
Little Colosseum, however, has massive changes to many of the top mons in the tier. They all play drastically different to what one would expect of the mons going in to a fresh metagame, and as a result teammates' experience with different LC tiers has no value almost at all. While you could argue a similar case in how mons function in say Doubles, which is a fundamentally different way of playing the game, the pokemon available are still gonna have the same moves, stats and options as in any other SV Metagame, and input can as a result be provided based on known interactions and movepool options from experience at a glance, making for a more inclusive team environment. With Little Colosseum we'd have to go to a doc, search for a mon and memorize every single stat change, ability change, movepool change etc (And some of these are stacked with changes). It's too much work and I'd argue too much to expect from managers and general teammates to have to fully learn what is essentially a whole different game, just to be able to give input in a slot in a tournament they're trying to win.
Not to hate on Little Colosseum, I find the concept intriguing and looking through the list many fun changes have been made. I just don't think it's suited for a team tournament related to LC. Not one bit.