Roman and Kylie first battled Ash and Brock and were easily defeated by them. They were then about to battle May and Dawn when Team Rocket broke into the restaurant and stole all of the food. Roman was upset by this and wondered what his father would say.
After May and Dawn dealt with Team Rocket, Roman and Kylie officially started their battle with May and Dawn. Despite putting up a good fight, they were defeated in the end.
This listing is of Roman's known Pokémon in the anime:
After the food was reclaimed the Trainers agreed to continue the battle. Blaziken started with a Blaze Kick only to be countered and then hit by Girafarig's Bite. Piplup then attacked Girafarig, along with Drifloon, with a Whirlpool and was finished off in a combination of Piplup's Bubble Beam and Blaziken's Fire Spin.
A character named Roman appears at the Seven Stars Restaurant in the English translation of Pokémon Diamond, Pearl, and Platinum and may also be battled in a Double Battle alongside a character named Kylie. However, the game Roman's Japanese name is リオ Rio and his only Pokémon is different from what is shown in the anime. In the games, Roman's father is the head cook, while Kylie's father is the owner of the restaurant.
This listing is of Roman's known Pokémon in the games: