Cruz, also called Cross, abandoned his Charmander during a pounding rainstorm, deeming it too weak for battle and revealing his early belief that only strength mattered. He later challenged Ash, using his Incineroar to defeat Ash's Charmeleon, then openly mocked Ash, displaying his arrogance toward trainers he considered inferior.

His antagonism peaked at Mount Tensei. After Ash's Charmeleon evolved into Charizard and defeated his Incineroar, Cruz snatched the sacred Rainbow Wing, linked to Ho-Oh, from Ash. Placing it on the Rainbow Rock, his "heart of evil" corrupted the wing, triggering Marshadow to brainwash nearby Pokémon into attacking Ash and his friends, highlighting Cruz's resentment and disregard for the artifact's spiritual meaning.

A crucial shift occurred when Charizard, though holding no affection for Cruz, protected him from the brainwashed Pokémon, acknowledging their past bond. This act of loyalty prompted Cruz to recognize Ash's worth as a trainer. He physically restrained his own Lycanroc, helping Ash reclaim the corrupted wing. Resolving the conflict, Cruz left on amicable terms with Ash, explicitly stating their rivalry would continue in future battles, marking his transition to a more respectful, competitive figure.