http://www.smashboards.com/showthread.php?t=197330
Every single move in that thread is a pokemon move Pikachu uses.
In addition, Pikachu can use Volt Tackle (Final Smash), Dive (Quick Attack Underwater), Fling (throw an item), and Protect (Dodge/Shield).
Haven't you noticed the stat differences in Ash's Pikachu as the generations of Smash progressed? At first his Pikachu managed to take down an entire flock of spearow. That one was released into the Pikachu tribe they found in "Pikachu's Goodbye". The one that emerged at the end of the show was sent by Pikachu to be Ash's new companion. Shortly after joining, Ash's original Pikachu was captured and placed into SSB. That's why he kicked so much ***.
For his efforts, Ash's original Pikachu was given an opportunity to retire with a beautiful female Pikachu. They breeded, and gave birth to two Pichus. The firstborn evolved and was quickly placed in SSBM. His younger brother Pichu's jealousy kept him from evolving, but through begging cutely (Pichu used Charm!) he managed to snag a hidden character slot. Competition was tough, and it was hard for him to win because of his light size. Overexerting himself caused him to get hurt by his own electric attacks. This hindered the happiness that would otherwise allow him to evolve.
Overtime, Ash's 2nd Pikachu had reached a high level and it was time to switch it for the new generation. SSBM Pikachu wanted to go home to Ash's 1st Pikachu and it's wife to take care of them in their old age/high level. Sakurai offered to let Pichu stay in the smash series and let SSBM Pikachu retire. Overjoyed, Pichu evolved into SSBB Pikachu. "Just as planned" laughed Sakurai.
This is why SSBB Pikachu wears the goggles of SSBM Pichu, and why Ash's Pikachu lacks the power and badassery it used to have.