After returning to Aspertia City, I visited the Aspertia Gym. I went inside through the classroom and I arrived at the battlefield in the back. I spoke to Cheren by the entrance and he told me that I had to battle and beat the two Gym trainers before battling him. I defeated the Gym trainers and left to heal my Pokemon after those battles since my Pokemon got injured a bit. I returned to the Aspertia Gym after visiting the local Pokemon Center, and I finally challenged Gym Leader Cheren. He sent out his Patrat first and I used my newly-caught Riolu against it. Riolu damaged Patrat, but I switched to Snivy to finish it off with Vine Whip. I used my Psyduck against Cheren's Lillipup next, but its Water Gun attack didn't do as much damage as I wanted. Cheren's Lillipup used Work Up afterwards to get stronger. I used Psyduck and Snivy to finally subdue Lillipup, and I won the Basic Badge from Cheren.