I attempted this set on showdown a few times:
Charizard @ Assault Vest
Ability: Solar Power
EVs: 252 HP / 252 Def / 4 SpD
Calm Nature (Atk-, SpD+)
- Flamethrower
- Solar Beam
- Focus Blast
- Dragon Pulse
It wasn't that bad, it's just it's 4x weakness to Rock that really hinders it. I just need a Pokémon before it to set up Sunny Day and this Charizard can usually 2HKO with Flamethrower or Solar Beam.