Quoted from BoJo:Get Peter Cullen or just use audio clips from the show if you are not going to pay him. Still won't make sense hitting Optimus in the nutts when you select Autobots and maybe they could replace him with a toy both sides would attack like Unicron.
The only way hitting Prime in the nuts will ever make sense is if they hire Cullen & write a script that has him training/sparring with you.
Honestly if they’re going to revisit the TF theme, it might be better to retheme a different game.