Change his Side-B to a 'boost' (complete with F-Zero X boost sound effects) which projects him fast in the direction he's facing, causing
high damage to anyone he runs into but also inflicting an amount of damage on himself as a cost to use the boost. His side B may be called 'Raptor Boost' but it certainly doesn't look like any boost I've ever seen.
I'm only half-trolling - I think the F-Zero series has its share of interesting mechanics that could be introduced (paying health to use a powerful boost, the 'spin attack' and 'side attack' introduced in F-Zero X) but alas, the fanbase would flip its **** if any actual moveset changes were given to Falcon, who's moves have been meme-fied to heaven and back. I think his Side-B is fair game though; that way Ganondorf's Flame Choke will be even more unique to his character, and Ganondorf could likewise have a few of his moves changed to further de-clone the two.
And maybe a couple of his Smashes and aerials could be changed, if only visually, so they have either a red or a flashing red/yellow glow around them, like when you do the Spin and Side attacks respectively in FZ-X. I don't know, maybe I'm blasphemous for wanting to properly tamper with a character who's been in Smash since the 64 days, but it's nice when a character's moveset is at least
remotely inspired by their game of origin - I know it's a tall order with characters like Falcon and Fox who are seldom seen outside their vehicles of choice, but adaptations have been made for Smash in the past.