Might as well hop on the bandwagon, ey?
1: Geno
I mean, of course. My favorite party member in Super Mario RPG, hailing from a game that introduced me to so many neat and wacky things that got me interested in RPGs to begin with, and who has a lot of interesting and varied attacks that would be cool to see in a party brawler like Smash Bros.
2: Klonoa
Admittedly, I never got much playtime with his original games, but I've always had a huge appreciation for the character due to a Game Boy Advance game that I enjoyed playing very much. I love his design, I enjoy the world he hails from, and I think it'd be a neat character to add to the list.
3: Phoenix Wright
The Ace Attorney games gave me a new way to enjoy interactive storytelling, with dramatic (and sometimes silly) twists and turns in the story, memorable characters and narratives, and a unique style of gameplay that has only further evolved in the various games that have spawned from the core franchise. Also, I used Phoenix Wright like mad when he was actually in a fighting game, Ultimate Marvel VS Capcom 3, so naturally, another chance to throw paper around and chuck evidence at people seems like fun to me.
4: Crash Bandicoot
If ever there was a mascot from Sony's side of the pond that needed to be in Smash Bros., I honestly think Crash fits the bill to a T. Huge fan of his tricky platforming games back in the day, just as big a fan of the N-Sane Trilogy remasters today, and with a new Fourth game around the corner, I'm hype to enjoy more of what Crash has to offer. His moveset would work quite well in Smash, I think, and I feel like now's the best time to make it happen.
5: Rayman
Incredibly nostalgic for Rayman 2 on my N64, I also thoroughly enjoyed Rayman's 2-D offerings in the modern titles Origins and Legends. I've always kind of wanted to see Rayman appear in something like Smash, and interestingly, it was actually due to the ArtsiOmni Smashified leak that I really started to think more seriously about it. Of course! It just made sense. And, it's also a longtime request of one of my best friends, so to see him get his wish as well would mean a lot to me.
Honorable Mentions:
Sora, Amaterasu, Lara Croft