Ryusemimaru

Ryusemimaru (nicknamed Ryusei or just Ryu) is the son of Utsusemimaru and Ryuko Matoi and rival of Calrem Joo.

Battle Against Rival
As Calrem decided, Ryu sent out his Chespin (nicknamed Otto) to beat Gekou, but he switched to Vibi then easily defeat Otto with Aerial Ace and Confusion. Ryu states that Vibi's attacks used super effective to beat his Chespin. He sent second Pokémon Stag the Heracross which is has Mega Stone to evolve into Mega Heracross then easily defeat both Vibi and Gekou then win the battle. Though Calrem lost his battle, Ryu help makes their Pokémon evolves into Mega Pokémons with using special Mega Stone-like spicer called DNA Evolver which is Kyurem's part and Samuel's possession. When they finishing his explanation, he starts his journey then say goodbye to his rivals.

Lumiose City
As Calrem and Charizard finally go to Sycamore's lab, Ryu reappeared in his lab and talking of them about mysterious crack dimensional portal. Ryu asking Calrem to second battle and he decided then sent out his Chespin, Otto and he chose Gekou the Frogadier which is Ryu's shock that Froakie was evolved. His Chespin was defeated by Frogadier's Bubblebeam and Water Pulse. He states that Frogadier was too strong for Otto, but he sent out his Heracross Stag then before used Mega Evolution into Mega Heracross. He easily defeating Gekou and Vibi just like previous battle, but only defeated by Bago the Mothim and Calrem win the battle. Ryu stating that three Pokémons were bonds with him. He went off to somewhere to catch strong Pokémon then say goodbye to his rival.

Route 7 and Daycare
Ryu reappeared again and revealed Otto was evolved into Quilladin and caught the Flabebe. He was also revealed that he was the son of Utsusemimaru and Ryuko since they were married.

Badges

 * Bug Badge (revealed in episode 15)

Triva

 * Calrem and Ryusemimaru were best friends and rival since they were childhood.