I don't think it should replace Outrage. Instead, it should be a move in Salamence's pool, since 'mence can't learn Outrage (at least in the current gen of the main games). That would provide a good differentiation between Dragonite and 'mence so people will have incentive to evolve/power up both.
I do think it should be a single bar move and be very similar to Overheat in time, power, cooldown, etc. Because in the main games, the two moves have the same power, accuracy, and effect (of lowering the user's sp.attack by two stages).
