Patch 1.10. No customs, 1111 Miis only.

Won't lie I had a hard time picking between Mewtwo or Ganon as worst (ಠ ᴥಠ)

To rate the viability skill on this tier list, let's say I think everyone all the way down to and including C tier are "good" characters and can be viable with a single secondary, and people in B and up can be viable by themselves. D and below need really good or multiple secondaries.