Roy's recovery is *** compared to marth's mostly because of his falling speed. Which should be kept as is (the falling speed I mean) give him his own style. Falling speed is a good and bad thing but it helps separate him from marth. If he got better rewards for hitting people rather than having to run in and back out for like >10% pokes that can often get you punished on hit anyways (which makes his falling speed a strictly bad thing since he's comboed easier), and hoping for dtilts you'd fix a lot of his problems right there. Yeah, his recovery sucks, but it's not his primary issue nor would it really need any buffs if he's fixed right.
Also adding tom nook is a bad idea and you should feel bad. Dixie is meh, but King K Rool deserves to be in before her as he's a villain and the series has no villain reps, but two protagonist reps.