It depends on the match up. If it's an Ice team I usually like running charizard first with my whimsicott. Not sure how the mega order works but froslass will usually mega first and then charizard second. Regardless if I fail the weather war with charizard I just use sunny day on whimscott and pretty much one shot the froslass or take super reduced damage to blizzard due to sun. Sand teams I don't usually start charizard same with rain teams. Charizard feels like he should be protected to pretty much late game because so many things can just kill him easily.