I'm assuming you're talking about the Typhlosion from MT with the Firestarter Poke-Power.
You can use the Power regardless of whether Typhlosion is active or benched. If there's a restriction, the power will say so in the text (it would say something like "if Typhlosion is your Active Pokemon" or "if Typhlosion is on your Bench"). Since it doesn't, you can use the Power in either case.
Just note that the energy you retrieve has to be attached to a benched Pokemon, regardless of where Typhlosion is when you use the Power.