Pikachu seems to me to have the trappings of everythign that makes a character great in this game.
Ways to gay really good characters, CGs on many top tiers.
Amazing manuverability, he has a good running speed, and at least an average fall speed and horizontal mobility. and he has the QAC which gives him some of the best manuverability in the game, albeit at the cost of making him as big as bowser for a small moment.
normally, hes small, which although it takes away from his range slightly (he still has some moves with great range.) along with his manuverability, it makes him really hard to hit, which is always a plus.
for a light character, he has a fckin FANTASTIC momentum cancel. i think his like 20 frame up air to completely neutralising side b, is probably second only to the bucket interms of helping a character survive.
hes one of the very few non-plank-able characters in brawl, since his projectile curves ledges,
t-jolt is a great camping tool, since it have very little commitment.
has great set ups for kill moves, like falling fair and rising up air.
and last but not least, he has a 0- risk kill move with infinite priority, that he can use to follow up other kill moves that dont quite do the job, he can gimp with it, and most importantly IT KILLS YOU FOR DOING SOMETHING CORRECT!
when you get hit by a kill move, you are supposed to momentum cancel, but pikachu kills you for doing this with thunder.
not to mention down smash is a minigame seperate from everything else entirely, and he can plank with the best of them.
hes amazing at edgeguarding snake, which he can initiate from anywhere on the stage with a low % grab
his offstage game vs falco is very good, which, again, he can do at almost anytime.
down smash wrecks ICs and combined with his ability to kill a non-DIing nana at 40 with thunder2, hes very good in that matchup.
he can run circles around DDD.
and he fares well against most other characters, and even tho mk and marth can give him the **** pretty well, I heard it said about pit a couple pages back, that he can camp all of his bad matchups to a winnable status, and pikachu is the same way.
and this is all just stuff that people are doing now. I think if anybody can master the up air footstool locks (which can be used to punish out of shield) and a couple other niche things with the character. he has the potential to be top tier.
of course... I could also just be biased because pikapika! is the number 1 ranked player in my region curently...