It's understandable to initially assume that it should have come with Titanmasters, as previous "Powermasters" had Titanmasters (Optimus, Dreadwing, Darkwing, Overlord, Getaway), and if Doubledealer had Titanmasters they would have scaled with those others... but now they won't.

Now we kinda need remoulds of the Rumble/Frenzy/Knok toy done as other Powermaster engines to scale with Knok and Skar. Something TakaraTomy probably would have done, if they weren't stuck with just releasing Hasbro product (they did it during Titanmasters, releasing various Targetmaster guns with their toys, because Hasbro were only releasing the heads as their Nebulan companions).