Dodrio is the much better option for two reasons:
a) He's a Stage 1
b) Chandelure should be the sole purpose of this deck. Metagross would make it to clunky, as well as taking up more deck space. Finally, the way I see it, Metagross should be a tech, not an attacker.
I like catutie's idea of Crobat Prime as a tech here. Start Zubat, quickly set up Crobat and Chandelure on the bench, Severe Poison, Mysterious Light from Chandelure and BINGO, 10 Damage counters per turn (If the burn and the Confusion hit tails)