The Fatal Five versus the entire Legion of Super-Villains

[Beyonder]

Tarik, the "Addult" LSV and the entire LAV rooster - that one who took over Orrando in the early 1980ies - versus the Fatal Five.

Since most of them are sadistic butchers, you know they won't hold back.

[Anonymous]

I for one am sorry they never did the sequel to the Adult Legion story they promised in Adventure.  I think in retrospect the writers felt maybe it was a mistake to reveal everyone's future, so they opted not to do another one.  
Too bad.  The Adult Legion was interesting.

[DoctorZero]

Oops.  The guest was me, DoctorZero.  For some reason it came out as guest.

[lastkryptonianhere]

Seeing how easy the few LSH that the LSV fought on the planet kicked their butts (Projectra, Ultra Boy, Chameleon Boy, Element lad etc) I would have to say

No contest the Fatal Five would kick their butts too ---- and Validus alone could wipe out most of the LSV who relied on stealth and sneak attacks until the LSH wiped them out.