Nice review of Pikachu, my friend. However, I dissagree with B^ (Quick Attack) being unreliable. Pichu's is much harder to control, although it zips you much further. But Pikachu's is really easy to control. The only disadvantages I would say Pikachu has is...range. As JKrew and Alan said, Pikachu is an up-and-at-'em, in-their-face character, which isn't good when he's got copious amounts of damage on him. However, he's good at both 1-on-1 and 2-on-2 matches, and very versitile. B> isn't all that great, and A^ aeriel while it looks cool and knocks your opponent away quite nicely only does 4 damage, where as it did about 12 in SSB. But still a great move.
Also, I agree with Alan about C.Falcon (eep...), DK, and G&W. And Mario and his tornado throw...that is the coolestness. I love hitting people right next to me with that. I just wish that they had either made Mario just a little bit faster (he's pretty fast for a plumber, but not that fast in SSBM), or slightly more powerful, or have slightly more range with aeriel moves. But Mario is an all-around great character.
And please oh please, DON'T start me on a rant about how much they messed Kirby up in SSBM from his previous awesomeness in SSB. I've already ranted about that somewhere before and I know I'll start again if you talk about him too much. I love Kirby so much, but...they friggin' screwed him up in SSBM. So many ways.
Now, how about a unique character I like to use called Ness?
Ah, yes. Ness from Earthbound series. Papa Krueger called him, "Bob's big boy," because he looks so friggin' pudgy in SSBM. Seriously look at his flippin' head... Anyways, Ness is extremely versitile and has an incredibly unique range of moves. First off, his double jump is incredibly unique, as he floats around spiffily. However, for his third jump, Ness must use his PK Thunder move into himself, which is incredibly powerful, but not always reliable when he's falling off the stage. It works well horizontally, but is harder to use when he really needs a vertical boost.
Now for his A moves. His normal A move is nothing fancy, just a boring old 1-2-kick. His light A^ move is a funny arm push up thing which knocks enemies away quite nicely. His A crouching move is a weak kick that only does 3 damage and has limited range, but can be used many times over in quick succession. Ness' walking A> move is a little kick that is fairly reliable, but is only really useful once the opponent already has a lot of damage. When he runs, Ness does a very useful and cool looking energy zap forwards. It's difficult to hit with sometimes, because it shoots out from Ness forwards, and its range is hard to measure. However, if you time it just right, it can forcibly push your opponent far away, and if the oppenent has enough damage, this is a great move to kill him with easily. Unfortunately, if your timing is off, it does minimal damage and leaves your opponent right in your face for him to attempt to beat up on you. For smash moves, Ness' A> is his good ol' trusty baseball bat. It totally smashes opponents away with lots of "force" (how far the target flies when hit) and damage, as well as darn good range. His A^ smash is a yo-yo which is hard to use, but has good range if you time it right. His A down smash move is also a yo-yo attack, and is also somewhat difficult to move. Ness charges it up behind him and then flips it forward in a rolling yo-yo attack. Good range, but timing can be difficult.
Aeriel moves! Which I forgot to mention the first time...
Anyways, these are the primary reason I use Ness in the first place! First is his normal A move, which Ness does a little spin with his hands out. It's a good move for knocking enemies away, but nothing too fancy. Next up is his forwards aeriel move. It's just like his dashing move, only in the air. You can zap your foe with it a bunch of times, and it's always fun to do several soft jumps and repeat this move on your belittled opponent over and over again until you smash them with something else. A^ is a powerful headbutt where Ness uses his freakin' huge noggin to smack peoples above him. Good damage, and easy to connect with. As Alan said, Ness' A down meteor smash aeriel move is quite killer, although the timing is move difficult now that it has a slight charge up time. But it's sorta like Ganon's powerful A down aeriel move--you can knock people into the ground and back up with a ton of power. His last aeriel move, and the one I use the most, is his backwards psychic kick. This does a ton of damage and has a lot of force to it. It's great for both dealing damage and finishing blows. Whenever your opponent is trying to recover from being knocked off and is trying to get back on, just jump towards them with your back to them and BANG! They are outta there!
Ness' grab moves are very powerful and fun to use, although Ness grabs somewhat slowly. But if you connect with a grab, you can dish out some serious pain. First is Ness' forwards grab move. It's sort of like Mario's forward grab move, only it's a psychic toss and not an actual toss. His backwards toss is very similar to Mewtwo's spin around and backwards throw grab move. Upwards grab Ness does a funky finger twirl and then hurls his opponent upwards with a powerful psychic throw. His last grab move is his downwards one, which he puts his victim beneath his feet and burns them, then blasts them away. Fun to use and watch.
Lastly, Ness' B moves are incredibly unique, and are useful in different situations. Normal B is Ness' incredibly powerful PK Flash which, once fully charged, does a massive 36 damage, and usually kills any opponent that is hit by it and has over 60 damage. PK Flash can also be controlled by the joystick while Ness is charging it, so you can blast your foe from a little ways away. While PK Flash has somewhat limited range, can be hard to control, and takes a while to charge, it is incredibly effective in free-for-all matches when your opponents are all interlocked with each other and not paying attention to you. But if you try using it on one-on-one matches...chances are that it won't work out very well. B> is PK Fire, which is Ness' longest ranged move. It doesn't deal massive damage, but it burns slowly and keeps the opponent stuck in it, especially if you use it over and over again. After burning your foe mercilessly about five times in a row, it's easy to just walk over and follow up with a quick bat to the face and send them flying. B^ is, as I already stated, a powerful but somewhat limited move. It also has a draw-back of a long recovery time after use. Finally, B down is the PSI Magnet. This move both protects Ness from most projectile moves AND heals Ness at the same time. This works well against Bowser's flames, Fox's and Falco's blaster, Samus's charge shot, Pikachu's Thunder Jolt, Mario's Fireballs and many Pokemon moves. However, it does absolutely nothing against melee attacks, and that's what your opponents will mostly be throwing at you. Sadly, PSI Magnet is just too limited to be consistantly useful, and is completely useless against projectile-less characters such as Marth or Ganondorf. Personally, I think they should have left this move out and replaced it with the awesome PsySword move from Earthbound. That move kills.
So, overall, Ness is a very versitile character, and can hold his own in any free-for-all or one-on-one battle, and works wonders in two-on-two.
+: His main strengths are his unpredictability, versitility, unique jumps, powerful grab moves and plain power with his friggin' bat.
-: His greatest weaknesses are his overall lack of range (except for PK Fire and his bat), sometimes unreliable third jump, and the fact that some of his moves are better against some characters, but are totally worthless against other opponents.