Well, I have yet to go over all the characters as much as I like, but heres my review on the ones I frequently use.
Sonic-I'm trying to main this blasted hedgehod, as I see a lot of potential in his moves, mainly the comboing potential of his rolls, and jumping up to get your opponents in arial combos. This strategy is lacking against characters like Kirby, and Pit, who can fly, but for every one else, its a good way to build up dmg to get them in KO range. That range however, doesn't really start until around 90-100%. Also, some of his moves are a bit wild, like his dair, which if you dont use properly, will send you plummeting off the stage. Overall, I see potential, but hes realisticly only a mid tier in no item games, since his Final Smash is his main KO threat.
Kirby-The main reason I didn't like melee, was Kirby sucked ***. He's gotten a major makeover however, giving him his KO potential back to his move set. He's also faster, making for an all around better Kirby experience. The fact that his Final Smash gives you some items afterwards isn't bad either. I don't think too many people will invest much time into Kirby however, which is why I place him in a Mid tier as well.
Link-Well, he fails in comparison to Toon Link, who is almost 100% than Link. His boomerang is useful on the way back, as it pulls opponents closer, and with some practice can be used to deliver a devastating hit with Links fsmash. He also retains his three his usmash, which Toon Link does not. Probably just a lower tier, but hes an old favorite of mine.
Diddy Kong-His bannanas are what makes him. Without proper use of them, hes just a semi quick character, with a good KO ability. Actually using the bannanas properly however, can give you free openings on your opponent, and allow you to spend less or more time in your defensive game, depending on how you prefer to play. His final smash is also entertaining. With proper use of his potential, I believe hes capable of High tier, if not top.
Ice Climbers-Well, their B-moves are almost worthless, with the exception of their forward b, but that counts as your triple jump, so use it wisely. The real appeal of the Ice Climbers are the fact that there is two of them, obviously. While charging for a smash attack, if your opponent attacks you, sometimes it will only hit the first climber, allowing the second one finish the attack, and deliver a counter attack of sorts. Being grabbed will aslo have the same effect, and in some cases, they will even grab the wrong climber, leaving them wide open for a serious blow. They have potential, but I think they've been toned down from Melee. Another mid tier.
Pokemon Trainer-This guy has potential for top tier, I know it. Three different movesets accounting for three different styles of play, and a character swtich that can easily be used to dodge(though it also leaves you open after the initial dodge), complete mastery of this character could prove to be devastating. High or top tier potential.