Maybe consider having Brock given rock tomb instead of rock slide (which is also pretty OP for this point in the game). I know this isn't cannon, but would you consider editing the base stats of riachu as well? So that we could still evolve Pikachu if we wanted to. Also, it learning iron tail so early pretty much just makes it far too strong far too quickly. It learns thunderbolt before discharge which is a bit weird and given its special attack stat, allows it to pretty much destroy anything.
So from a balancing point of view: Pikachu is waaay overpowered.
