I thought it might be a Fire move too; but none of my Magmortar could learn it, for some odd reason. ~_~ Neither could my Charizard starter. I finally took a hint from a YouTube clip and chose the Arcanine I'd evoved recently--though it's still confusing that he could learn Fire Blow but other Fire types couldn't.
Moving on from there ... I've cleared the Ricyan City gym by now and am searching for the next one. Judging by Soka's final remarks, I'm guessing that Dig will be necessary to get past some obstacle; howver, the closest roadblock that I haven't been able to pass is the one set up by Team Steam. Since I can't tunnel around them, could you please tell me how to unblock the path? Many thanks!