Here are a is what the game said https://www.youtube.com/watch?v=KbHPpdPhlic
50 cent said "“Hip Hop is Black music, without question, and, unfortunately for some people, it’s tough to accept that you have a White artist that does it better than Black artists,” 50 Cent says during an interview with Music Choice. "It is what it is. You can get like whoever you think is the best Black artist and stand them face-to-face in a room with Em and he will eat that [guy] alive. Right now if you had 'em prepare themselves, whatever way they would have to prepare themselves to come battle…I bet what I have, everything” that Eminem would win."
Eminem would beat Busta Rhymes. I've only heard one diss song by Busta Rhymes on Hail Mary 2003 WITH Eminem. Honestly, on that song, Busta Rhymes did better. Overall, listening to songs like Nail in the Coffin, Bully, and Girls, Eminem wins hands down. Eminem in his battle rapping career has beat Insane Clown Posse, Everlast, Ja Rule, Benzino, Canibus, and Cage.
Eminem would win the rap battle do to his creativity. His lyrics are much more complex than anything that Busta Rhymes has ever produced. This alone allows Eminem to achieve technical success that Busta Rhymes could only dream of. Busta Rhymes also writes less of his own lyrics than Eminem which further puts him at a disadvantage.
Busta Rhymes would win in a rap-off between him and Eminem. The reason is simple--Busta Rhymes is has more experience in the medium. Eminem is talented with great rhymes, but he's just a punk from Missouri. Busta Rhymes was born in Brooklyn, where the heart of rap exists. Eminem's got talent, there is no disputing that. Busta Rhymes is just better because he's lived the life more than his counterpart.