I started up a yellow version for the purpose of gaining knowlege of Pikachu exp gain. I realize this might be different for the other versions, but it fits my needs as an accessable way for me to check level gain for a Pikachu. BUT ANYWAY HERE ARE LISTINGS FOR LEVEL GAIN AND STUFF

ACCORDING TO YELLOW VERSION 

total from spearow- 46 Spearow @ ~ level 4 (33 exp each)= 1518 exp total 

Lvl 5 = 91 to 6 @ 1427 left

lvl 6= 127 to 7 @ 1300 left

lvl 7= 169 to 8 @ 1131 left

lvl 8= 217 to 9 @ 914 left. Learned Thunder Wave

lvl 9= 271 to 10 @ 643 left

lvl 10= 331 to 11 @ 312 left

lvl 11= 397 with 85 left to level 12. Learned Quick Attack

So that means Pikachu is at level 11 and his attacks should include (from the new movests)

Thundershock, growl, tail whip and thunderwave. This is just really important for the rest of the series :D