Pikachu
Basic Moves
On the ground basics
Controls Description
Damage
Launch meter
A Headbutt
2% 
 
Forward or back + A Short-range electric shock
14% 
 
Forward or back , A Side kick
8% 
 
Forward , forward , A Lunging headbutt
9% 
 
Up + A Flip kick
14% 
 
Up , A Tail strike
9% 
 
Down + A Tail sweep
12% 
 
Down , A Low tail strike
9% 
 
B Thunder jolt
6% 
 
Up + B Upwards jump*
0% 
 
Down + B Electricity**
9-21% 
R, R or Forward Flipover throw
12% 
 
R, Back Back electricity throw
14%
In the air basics
 
Controls Description
Damage
Launch meter
Kick
12% 
 
Forward + A  Electric side drill attack***
3-15% 
 
Back + A  Back kick
12% 
 
Up + A  Upwards tail strike
10% 
 
Down + A  Downwards electric attack
10% 
 
Thunder jolt
8% 
 
Up + B  Upwards jump*
0% 
 
Down + B  Electricity**
9-21% 
*This attack causes no damage.
**If opponent is next to you, more damage is caused. If they are in the air above you, less damage is caused.
***Depends upon how many times you hit your opponent.
Combos
Strengths
Pikachu is a pretty quick character so you need to use this speed to get close to your opponents to set up throws and the flip kick.  Don't bother using the short-range electric shock or electricity too much because, although they are launchers, they are easy to block and counter.  If you can get a double upwards jump, that's a great way to get away from someone who's invincible or has a weapon.  Or avoid an opponent who's coming after you and jump down on him with the electric side drill attack.  You can then set up a flip kick or a throw if your opponent is blocking.  This should get you some kills and keep you away from being launched yourself.  However, Pikachu's best chance for racking up kills is to get the bat or beam sword.  Hit back or forward + A with either of these weapons and you'll spin and hit anyone in front of or behind you.  Or wait for someone as they comeback from a launch and hit them again.
Weaknesses
Pikachu's three best launchers all have very little range: the flip kick, the throw, and the short-range electric shock.  To beat Pikachu, use projectiles from afar and quick mid- and long-range attacks.  Pikachu's throw isn't as effective a launcher as his flip kick so, if you get in close with him, block.  When you launch him, try to get underneath him as his downward moves have average priority at best.  Or if Pikachu is trying to come back, set up for another launch by the edge of the board--if you force him to fly above you, you can get him as he falls down.