Another advice: don't confine yourself to steadfast rules of Pokemon. In other words, saying that Pokemon only live in the areas they live in in the games, and that the ONLY difference between Ember and Flame Wheel is base power. Ember is shooting small bursts of fire. Flame Wheel is cloaking yourself on fire and tackling. Also, if a Pokemon has used Ember for years but just learned Flame Wheel, it's reasonable to assume that the Ember attack might be more powerful than Flame Wheel simply due to experience and being comfortable with the attack. The anime has shown many times people with more than 6 Pokemon on hand, so game rules aren't universal rules. So just because the anime and games and manga say something is such a way, doesn't mean you can't turn the rule on its head for the sake of your story.