because Guest characters don't make the game. I just look at the roster of the KI characters where there should be a full range of interesting playstyles for all players to try their hands at, the guest characters are sorta like extra sprinkles on a sunday and they shouldn't really fill in a playstyle that could be done by an original made character. Like how Rash is mostly Rush Down with a fun gimmick of him being a zipline character too, or Arby playing with resources unlike Spinal, only he's more focused on tanking and hard hitting combos unlike Spinal where he's more on lockdown and limiting the opponent's options. These are fine because they play off of existing playstyles that the KI roster has.