Counter is a move in the Pokémon games that Cinderace can learn. Max Pyro Ball appears to be a Max Move version of Pyro Ball, another move Cinderace learns. In Japan, the attack is rendered as ダイカエンダマ, of which one translation is Dai Fire Ball. Pyro Ball in Katakana is カエンボール, which could be translated as "Flame Ball". So in the original language, the attack and the move may be unrelated.
As an aside, while G-Max Fireball was introduced later on, it is likely semi-relevant. Its name in Japanese is キョダイカキュウ, which could be translated as Kyodai Fireball. So Max Pyro Ball does not have a direct tie to that move.