I'd need to check whatever you said about the combos to be sure you're not trolling me. But to answer question, the "tier gap" (difference between the character most people considers the best and the one considered the worst) is significantly smaller than most fighting games out there.
Think this way: i'll give some examples of characters for you to compare and in the end, try to do the same exercise with Skullgirls and see if you find a similarly blatant difference in potential. And being a joke character isn't an excuse. Fukua is a joke character and it's damn viable in almost any team.
In vanilla SF4 we had Sagat vs Dan
In SF4 Arcade Edition we had Yun vs Dee Jay
In UMvC3 we had the entire cast, the announcer and the NPCs on the background vs poor Hsien-ko (Kidding. Vergil vs hsien-ko)
In MvC 2 we had Sentinel vs Servbot or Amingo
In SF5 until EVO, we had Nash vs FANG
Marvel is the worst offender on this problem IMO.
Compare the damage, bars spent, number of inputs and time of each combo in this video
To the tournament standard Vergil
You get the idea.
Even in team based games, the characters themselves must hold their own weight somehow. In skullgirls the entire roster has a fairly good ammount of tools and the damage dealt is never obscenely low compared to the effort in the BnB. On the flipside, no one has an insanely abusable technique (no infinites because of IPS, burst baits are mind games and there's no 100% sure way to reset an opponent every time, no ridiculous bug that changes everything in the competitive scene, etc.)
With that, every character is viable, most teams could give you a good result and you don't need to abandon a character you like to get a "cheap" team that can do a 100% combo with little effort.
Hope that answers your question
