how are you gonna judge beats that are totally different?
what you need to figure out before anything else is judging criteria... because if you are not gonna have a set standard of sounds..
then at least set up some guidelines because...
for you to compare one beat to a totally different beat with a totally different set of sounds... with a totally different feel... with a totally different vibe.. is gonna be hard.
not to mention this whole "theme" thing is quite objective.
"grimey" beat battle.... well hmm not everyones perception of grimey is gonna be neccessarily the same... so in this case what would you do?
if its all out.. lets make it all out... lets throw in everything... sampling.. .sounds... any drums... whatever the fuck you want..
and just see who brings the heat hands down if thats how you are lookin at it...