OK
1. D3 is not totally helpless. What he is though, is a bulky slow character who hits things away too far to combo, unless you fight a Spacie and can 0-death them off of Uthrow. He gimps offstage in literally the stupidest and most obvious ways, and yet it's probably top 5 in the game because nobody can challenge the kind of range he throws out. He's still stuck in the Brawl mentality of "shield and punish" or Ftilt for spacing, because the rest of the character is booty cakes at approaching or offensively applying pressure.
If you were to take his Fair's range, and ask me if I would implement that move in a Smash game, I would tell you that you are ridiculous. Yet that one move is probably his saving grace from undeniably being the worst character in this fast paced "do your opponent dirty" kind of game. He's bottom 5 somewhere, unless every MU you get is Spacie.
2. Ganon is not hopeless. He's outclassed. Big difference. This game does not favor slower competitors, and he suffers immensely from the unfixed shield pushback. The list of what Ganon can punish OOS has dropped dramatically because of that. What did the game introduce more of? Short, annoying characters who jank around shifting mobility or momentum or do low attacks. Oh yeah, they tend to be pretty safe on shield. OH YEAH, let's count all the new projectiles and the new Brawl characters coming with range! AND Melee people got buffed?!?!? That's like 80% of them... Guess if you can't keep up, you get steamrolled. That's the life Ganon has, no matter how good his character otherwise is.
Part of me doesn't want to believe that he's bot 5 in this game, but honestly Ganon is not viable in this game. You could argue that he's basically "not' viable in Melee, but in this case it's a done deal that he will not be viable no matter how many top players you throw under his wing. Period. What Ganon lacks will keep him down for awhile, unless he gets buffed in huge areas like dashing/grab range or crazy stuff like very fast Fairs. I don't necessarily want to see Ganon tinkered with, beause I enjoy him a lot actually (grab a guy, ruin his world)
3. Squirtle has a below average kit, with tricky goodies sprinkled in, and pretty good mobility. He's the least "bad" of these three because you can at least try to play him dynamically and work things in your favor. There's no real alternative approaching or defensive gameplay for the other two. Because he's short and annoying, he's destined to not totally suck! You think I'm joking, but it's the law of this game and if you look around it's apparent lol.
I dunno if I would put Squirtle in bottom 5, he's "alright". I would put him in the bottom half of the cast no doubt about it, but I dunno if he's worse than people like G&W TL Luigi etc