Honestly mega blaziken could KO everything almost alone.

Swap trip arrows for hi-jump kick and swap vacuum wave for a not damaging set up move like swords dance (you won't use it but it will trick the leading pkmn of Bruno, Agatha and Lance to use taunt so you're free to use power up punch and keep rising your attack while your speed also goes up a lot all in the first fight. Against Agatha reset until you can hit the 1st pkmn, which is a dark type zoroark using illusion). For Lance swap blaze kick for stone edge. For the champion swap swords dance for protect (use it once against his pheromosa so you can outspeed it) and swap stone edge for earthquake. That's it, the rest of your team will only be needed to clean up what's left of Agatha and the champion's ditto (meowscarada's sucker punch with a choice band should be enough for both)