SNRise

You can't go back. You're still locked out of Reborn City for this badge and the next two after that. For Charlotte I always found that bringing your own fire team works like a charm. Her Pkm aren't particulary good, the field boosts are completely over the top, so even resisted hits deal sizable amounts of damage and her best Pkm, Volcarona, is neutral to fire and gets completely obliterated on the field. Plus don't forget stealth rocks.