I'd like to point out that Fortress Maximus, Metroplex, Omega Supreme, Grimlock, probably Skylynks, Slag, Snarl, and Sludge would likely take more (or far
more) chakra to summon than Optimus Prime (using the original animated timeline). Combiners are a grey area as the require several units to be summoned...
but the total level of chakra to summon all the pieces would be more. Not only is Optimus Prime a lead from the front kind of general... but he is a civilian
model. He'd have no reason to be the most expensive to summon... even considering the Matrix of Leadership.
Going with some of the more recent timelines... I can see one where Naruto keep summoning Minicons... which are like sentient fusion engines that got enslaved
because equiping them grants you superpowers. Naruto is told he isn't using enough chakra and the keeps adding more until he manages to summon the Requiem
Blasters compounents. At that point he manages to drain off enough chakra that he ends up summoning Nacho Prime and a few minions.... which are immediately
drafted as pants.
more) chakra to summon than Optimus Prime (using the original animated timeline). Combiners are a grey area as the require several units to be summoned...
but the total level of chakra to summon all the pieces would be more. Not only is Optimus Prime a lead from the front kind of general... but he is a civilian
model. He'd have no reason to be the most expensive to summon... even considering the Matrix of Leadership.
Going with some of the more recent timelines... I can see one where Naruto keep summoning Minicons... which are like sentient fusion engines that got enslaved
because equiping them grants you superpowers. Naruto is told he isn't using enough chakra and the keeps adding more until he manages to summon the Requiem
Blasters compounents. At that point he manages to drain off enough chakra that he ends up summoning Nacho Prime and a few minions.... which are immediately
drafted as pants.