Ivan Drago vs. Clubber Lang
Since Drago killed Apollo and Gunn was pathetic, it's the two biggest Rocky enemies going one on one.
Clubber beat Rocky, and then lost as Rocky came back even faster and clearer minded.
Drago lost to a fully energized(considered to be the strongest version of) Rocky, but gave Balboa head trauma in the long run, and even gave him nightmares.
Here are the two questions:
1. Who was the better Rocky foe?
2. Who would win in a 10 round match?