it all depends on the match ups. i could as easily say:
going full out, mm could certainly take out skrull and ronan (whirly's right, he's a TOTAL jobber) with a single, almost instaneous tp assault. that would quickly give the jla a good numbers advantage.
then: gl holds off ss, supes holds off thanos, ww and mm take out drax while firestorm holds off quasar and cm and flash deal with nova. when drax is tied up, mm takes out nova (if she survived flash and cm togther) with a full power tp blast (she has been assaulted successfully by a telepath in the past). that leaves things at:
ss, thanos, and quasar
vs
supes, cm, mm, ww, flash gl and firestorm
so: cm and mm take quasar
gl and firestorm take ss
flash ww and supes take thanos. the 3 of them should be able to hold him long enough until the others are finished and can help them polish him off.
jla wins.
😉