Growlith problem

do you know the exact IVs of the ones you hatched as opposed to the one you already have?

Arcanines make better attackers than defenders. Attackers shouldn't raise their cp too high.

Evolve and hope you don't get bulldoze, and you will hopefully have two good attackers.

You can do both. Power up the one you already have to arround 2000CP and evolve another one