You’re not quite understand our predicament here.
This is a strategy game, see? Meaning you have to use different characters and disk in order to counter and defeat specific characters (any character and disk are useful given the situation you are in).
And I’m paraphrasing Mr. Huph when I say, the perfect team is like an enormous clock and it only works when all of the cogs mesh together.
But if characters like Sally and Rex had their power increased ten-fold, all strategy is no longer in the cards for anyone and your team is pretty much done for. Especially in friendships where you have a fixed team.
So, not necessarily make them like they used to be, but just to the point where they can be useful in a fight but at the same time, can be countered and defeated whenever people comes across them.
For instance, any character that can utilize either invincibility or beserk like Hades or Beast is a great counter for Sally. They go through her poisonous fog and get to her before she gets to you.