Round 1: They are in Base Form and can have up to six emeralds
Round 2: Metal Sonic got Eggman's army while Black Doom gets his Dark Arms
Round 3: They both have transformations
Bonus: Metal Sonic has Sonic with him and Black Doom has Shadow with him and they are all in base form (Sonic will not be going all out)
i should post my opinion
Round 1: Metal Sonic because of a higher Destructive Capacity and more abilites and the ability of coping Black Dooms techiniques
Round 2: It can go either way but im in favor of Eggman's chances considering they have their heavyweight robots and the Black Comet is not going to do anything to a robot
Round 3: Metal Overlord had to be taken down by 3 super forms instead of 1
Bonus: Metal and Sonic will take this