Well the *Prime* version would be the most logical choice since that series aired around the same time MLP: FiM did, but do keep in mind that it is still *Parallel Universal*, and though it does have the same Autobot team from TP, it is still it's own reality with it's own unique canon to make it more compatible with MLP: FiM lore, so to be honest it can be which ever "Prime" the readers would like it to be.
*Reads very carefully*
Ok, so, what you're saying is the the Optimus Prime from the G1 universe would be the most likely Prime in this scenario, but it can be whatever Optimus that the audience wants.
Right. Had to think about that one for a second there.
Ok, so, what you're saying is the the Optimus Prime from the G1 universe would be the most likely Prime in this scenario, but it can be whatever Optimus that the audience wants.
Right. Had to think about that one for a second there.
Exactly, it's just a whole new reality made specifically for this story, but it still contains many elements from all variations of the entire Transformers Franchise, so it can be whatever the audience wants it to be, G1 Transformers, G2 Transformers, Transformers Cybertron, Transformers Energon, Transformers Animated, Transformers Prime, the Live Action Transformers Movies, or whatever other version you like better, just take your pick & imagine Pinkie Pie being thrown in a parallel version of that world made exclusively for this story.
Right. just had to get it straight. You spend too much time on the TFwiki or jumping between continuities and your head starts aching something awful.