>>50733657Update:
We kicked Clay's ass. I delayed Gastly's evolution 'til Lv 43 so I could get Destiny Bond so that Gengar could take something down before going down, and it just so happened to be Clay's big bad Garchomp.
The last Pokemon I brought was Azumarill, who helped out against Mamoswine, but was unfortunately too weak to try and fight anything else after, but Gengar and Gallade were able to clean house and win the day.