I entered the Mossdeep Gym and I went around trying to find Gym trainers to battle. I had to move some switches in order to access other areas and I had to leave the Gym soon since my Pokemon got injured. I returned to the Gym after visiting the PC, then I finally reached Tate and Liza's location and challenged them. They sent out their Solrock and Lunatone and I used my Blaziken and Pelipper. I had Blaziken attack Lunatone with Sky Uppercut and Pelipper attacked both Lunatone and Solrock with Surf. Those attacks did some damage, but Liza and Tate healed their Pokemon. I eventually switched Blaziken with Manectric since Lunatone had attacked it with Psychic and I won that battle with Pelipper's Surf attack.