Gaming Charizard - Overheat or Blast Burn?

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I have a Charizard on my Pokemon Emerald which is fully EV-trained and has great IVs. It's generally an offensive Pokemon (sp. Atk with Modest nature) teamed up with a Baton-Passing Espeon which can pass over stats from Calm Mind and Double Team. I am wondering if I should replace Overheat with Blast Burn by trading it to my LeafGreen game which I still have the Cape Brink tutor freed up on, since I'd rather just have Charcoal attached and do as much damage as possible. Obviously, as is the case with Overheat harshly reducing Sp.Atk, I'd prefer to save using it for the last Pokemon since it comes with the serious side-effect of missing your next turn. What would you recommend?