I feel like Link, Toon Link, Diddy Kong, Rosalina?, Shulk, Mega Man, Peach, the Villager?, and Sonic are one of the other characters who aren't linear. The Links can switch from walling out people with projectiles, spaced close combat, or trickster setups. They force players to not only manage their projectiles, but play styles as well. With pivoting, their Ftilts are dangerous because of their range and Link could bait out an action to Dash Attack out of a dash dance or perfect pivot. Messing around with the two makes me think that they can really pull of a ton of mind games and it makes sense since in the Zelda series, Link is a versatile hero. Fishing rod on Ganondorf anyone? Or using a bottle during Dead Man's Volley?
We've seen what Diddy Kong can do and it's mostly the fear of D-throw to Uair that allows Diddy to get away with it over and over, but Diddy can and will make use of his other tools like Dtilt comboing into itself, his other throws, the decision of using or not using Banana Peel, etc.
I haven't seen an offensive Rosalina yet, but I think it can be pulled off. It's the issue of she is a defense-based character, but that doesn't mean she can't be offensive-defensive. We've see how strong a defensive Rosalina can be with Dabuz, but I want to see an offensive one and see how well that play style does. If someone could switch on the fly of defensive to offense with Rosalina, it would be dangerous. Let's also mention that Rosalina is sort of a puppeteer character. Yes, some characters will wreck Luma if Luma's out, but that doesn't mean Rosalina can't use Luma to distance herself from her opponent or even bait them to go over Luma and Rosalina will punish by herself.
Shulk has the Monado Arts and with customs being allowed, you'll have to deal with default Shulk, Hyper Arts Shulk who can be a glass cannon or a stone wall, and Decisive Arts Shulk who'll prolong his arts for longer.
Mega Man has Zucco and NinjaLink who have different play styles. It's sort of like the Links of either being projectile-based or melee-based. The only thing is I haven't seen either of them play a lot, so I don't know if Zucco and NinjaLink can play both projectile and melee. There's also the whole using Air Shooter (Uair) to force an option like how GimR uses Mr. Game & Watch's Uair.
Peach is a technical character and being able to fight with an item means mind games. The only issue: no major results as far as I know and it's difficult to use a character like her. Sure, Shulk's technical too, but I don't think he's as a crazy as Peach. That said, it will be a while until we see Peach at a dangerous level. Quick float release expands her basic movement options of walk, dash, jump, and float to include short hopping, pivoting, perfect pivoting, dash dancing, foxtrotting, and quick float release.
I'm not sure about Villager, but in a way, I'd say the same with Mega Man and the Links, but I'm going to leave it at that and prevent myself from making myself look (more) like an ***.
Sonic's speed alone allows him to mess with people. He can takes things slow or fast. Add in the fact he's his own projectile and then his ability to just run up to you and beat you up and Sonic's a typical annoying speedster. The Flash, Spider-Man, and Sonic didn't win through brute strength like Superman or planned and backup-planned strategies like Batman, instead, they won through creativity and abusing their speed. We've seen 6wX pull things off on the fly.
That said, that doesn't mean say, a Mario or Zelda player can't get creative.