Based on your main choices ,Toon Link may be a workable character, but given your "speed" complaints and the fact that TL often just wants to camp to hell, that may be a very poor choice for you. Falco can do a little bit better, but still often fairs best defensively. Snake is also often better off defensive, even though he hits hard up close. And even if you can do ICs CGs, the slowness will KO you before your opponent does. Marth is also a character who requires patience.
Either go MK and go ham (Nairo would be a good player to watch a bit of footage of - he's really aggressive, but still very safe and a strong player), or Zero Suit Samus (fairly fast, good strings, KO moves - if you can use the armor, serious bonus points). If you learn to QAC and some of the CGs, Pikachu may be in the realm of reasonable, but then Olimar is a nightmare to deal with (who is also campy, so probably no).
As a side note, If you can play Diddy Kong in PM, you might just choose to pick him - he's got good options with all his bananas and glide tossing, and you can play him rather aggressively since bananas can provide a good bit of safety for attacks or grabs.
Also what those above me said. Above all, pick someone at C tier or above (and if you pick Fox, Wolf, or Falco, you NEED to at least briefly prepare someone else not named Snake to fight Pikachu, as Pikachu can zero-death all three of them out of a grab at 0% if the Pikachu executes properly, and you can't do anything about it except not get grabbed). Also prepared to have to deal with not getting grabbed by ICs (with MK you can try to space rising dair on shield and nado to landing or just land to refresh jumps - with others things get stickier, though ZSS and Diddy Kong have a relatively easier time because ZSS has good range and Diddy Kong can throw stuff at them. Snake is also good at beating ICs)).
TL;DR:
You could make TL, Falco, or Snake work, but they're all strong when camping, so they might not fit you.
Marth requires a ton of patience, and ICs require more, and some training - probably not good choices.
MK, ZSS, and (possibly?) Pikachu can be somewhat aggressive and have good MUs - probably choose from this list
Diddy Kong is worth noting because his bananas and glide tossing allow him to be played aggressively, also a possiblity
If you pick not one of these three, don't go below Pit on the tier list, and be prepared to fight ICs by avoiding being grabbed
If you pick Fox, Falco, or Wolf (or Snake), have a backup to deal with Pikachu, who can more or less zero-death all of them out of a grab (you WILL take 100+% if they do it right, even if you manage to survive).
Characters who beat ICs/do well against them: MK, Diddy Kong, ZSS, Snake, Toon Link (all about camping them).
