WWE 2K15

I did this in a regular One on One exhibition match against the AI. To my knowledge the fastest way to unlock an NXT character is to start a My Career mode. Once you finish the Performance Center tutorial, you will unlock Rusev for play. Even though his default brand in the game is RAW, he counts to use towards this achievement. Other NXT superstars include Adrian Neville, Sami Zayn, Corey Graves, Bo Dallas, and I will edit this to add any others as I unlock them if there are any more.

This can be done on any difficulty in any One on One match I believe. To make things easier for yourself, you can go to the game Options menu and edit the Game Balancing so the AI reversals are at minimum, making them reverse almost never. The game itself is already fairly balanced as far as characters go, so even though Cena has a much higher overall than most of the roster, it won't be too difficult to beat him with a lower overall character.

I got this achievement in exhibition, i chose adrian neville vs john cena.

didn't have to do this using my career just a regular one and one.

can be done on easy.