Alright got a bit further last night than I intended, turned on today after completing the Rock Tunnel and catching my first non-Charmander pokemon, Vulpix! After a bit of trainer battling and grinding, here's what I'm looking at heading into Celadon City to take on Team Rocket and Erika.
Charizard - Level 41 - Mega Punch, Flamethrower, Wing Attack, Steel Claw
Vulpix - Level 24 - Confuse Ray, Will O Wisp, Ember, Quick Attack
The basic strategy for the moment is Vulpix leading off so she's getting some experience regardless because I really need her level up quickly. If she can take the opponent with her annoyance technique (Confuse, Burn), she does. Otherwise, swap out with Big Brother Charizard and all is well. My Charizard is an absolute beast, only fainting once his entire life, due to poisoning on the way to Mt. Moon. It is really nice to finally have a second pokemon for varity though.