On their third encounter, Miles had his Flareon form unlocked, and could finally match Geo the Growlithe in raw physical power.

...

...but only physical power. Geo had experience and training over the 'vee, as well as a greater mastery over Type Energy. The Growlithe is merely toying with Miles - sure, the vee is getting a hit in, but he's going to lose this fight.

Just as Geo is about to finish Miles off, a blue streak grabs the Eevee and disappears with him. Geo's flaming fist hits just the ground, covering him in shattered concrete.

Note: Geo is indeed a Growlithe. He has a complex about getting stronger, and desperately wants to be an Arcanine. His costume/armor is meant to make him look like an Arcanine.

"Why not just get a fire stone?"

Evolution stones and Type Energy in general, in this world, is very rare and in low levels. Geo in fact almost got a Fire Stone, but it was snagged by Pat.