Looks pretty solid. Here's a tip that I found out the hard way. Don't fully evolve your pokemon until they are higher leveled because it takes WAY more experience to level up if they're fully evolved. At this point in the game, you seem to be in good shape. You're gonna want to be around lvl 75-80 for the E4 according to what I've been told.
As a compairson, here is my team and progress.
About to take on Sabrina
Wartortle: Lvl 51
Golbat: Lvl 50
Gastly: Lvl 62
Pikachu: :Lvl 62
Growlithe: Lvl 55
Ryhorn: Lvl 48(most recent member)
