One of the things we should try, as a community, to tell new players is that it's abundantly clear that developers only balance certain characters for "serious" 1v1 competitive play. After 3 previous installments, no developer could look at the kits of D3 or Bowser compared to Sheik and ZSS and say "Yeah, these characters will go about even." We know what attributes pay dividends in 1v1, and we know which characters have them. You're free to choose a free for all type character, but you should know what you're getting into.
But I wonder if it has to be this way. Firstly, I have to say that I don't envy the developers for having to balance for casual FFA play. A brief yarn for illustration: When I was a grade-school brat, I played a ton of Melee, in thoroughly casual fashion. In the first three years or so of my career, I don't believe I used the Shield nor the Roll option even once. I had no concept of defense. How could any developer have balanced around a player like me? A good half the gameplay stood before me, and I ignored it entirely. If I were starting out today, I would have no concept of guaranteed combos, or auto-cancels, or most of the subtle things that go into making a character tournament-viable. If Melee Ganon had a few more tricks up his sleeve against Fox at top-level play, my friends probably would have carried on throwing Warlock Punches at me in what I might now identify as the neutral. We'd never have known. The only time I used Shine was after down throw, or to make Samus mains cry. I do, however, give my third-grade self some points for thinking that NTSC Fox's UpSmash was a very silly move. Game balance was not entirely beyond me.
My point is that developers can probably buff heavy hitters for 1v1 play without much upsetting FFA battles, and that they have heretofore been overly cautious in this area. Slow characters are inherently at a disadvantage in gathering items, which could offset any buffs. Furthermore, while Fox isn't going to be getting into the thick of an 8-way battle, that doesn't mean he's a bad FFA character; he only requires a more hit-and-run oriented play style to do well, which nicely accommodates different sorts of players. Not everyone wants to just run in, damn the torpedoes, and do 15% on every hit. Bottom line is, I think it would be much more difficult to ruin FFA than many developers and players think.
If Ganon had a faster jab, or if heavies had better frame data, I truly don't believe that the FFA world would come crashing down. The Smash system is more robust than we give it credit for.
One last Melee memory: While I was ride-or-die with Fox, my elder brother dual-mained Roy and Ganon. Naturally, I chalked up my victories to my superior play skill. I apologize for nothing. I never won a wrestling match my whole childhood, so I took what scraps I could find.
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