There are numerous unknown DJ battles that were witnessed by a few at parties, dances, & showcases. These DJs only known to the world via competitions do not know those same DJs were already defeated by none other than SGDJ. Given that fact, if these well known world champion DJs were already beaten by SGDJ, then SGDJ is the Supreme Grandmaster by the secret DJ battles that these DJs only know about but deny since it is true to their own style mirroring that of their true master.
Of the known DJ Battles, no one beat him. He first faced DJ Dooku, a masterful scratchsman & very strong in the Force. SGDJ proves too much for him & he relies on a hamster style fader triple clicker in order to escape with his rep. The second DJ fight we gawked at was against DJ Sidious, who is similar to SGDJ's style. The DJ fight ended in a draw. A world champion who was equal in skill to SGDJ could only come to a draw. However, judges are seduced & djing is automated now so NBC. Always calm. Mask?