LogFAQs > #967790456

Your Infernape and Crobat should be able to handle Aaron easily, though with your current team you might need to just brute force one of his Pokmon.

Get a grass move on one of your special attackers they should be able to sweep Bertha. In lieu of that water and ice attacks generally work well. So your Galie and Gyarados can handle it.

Just let your Gyarados take care of Flint.

Mr. Mime and Gyarados can take care of Lucian easy enough.

Cynthia is the only really tricky one. Magnezone could handle her Milotic. Galie should be able to chunk out Garchomp. Infernape handles most the rest. Ideally you can end up in a situation where she switches Garchomp into your Infernape. When she does switch to Gyarados for a free Intimidate on the inevitable Earthquake. Then switch to Clefable (seriously, evolve this thing) on the Dragon Claw, switch back to Gyarados for another Intimidate. And repeat until it's toothless.

But the big thing is evolve your Clefairy and then go to the Move Relearner and work on some movesets. There is no reason that Gyarados has Bite instead of the much better Crunch. Infernape really wants Close Combat.

I probably would use Magnezone over Crobat. But if you are going to use Crobat, sub out Venoshock for Confuse Ray.

Honestly, the only real resources any of this needs is a grass TM like Grass Knot and a Moon Stone.