I would say a Max of 3 Panaceas/Greenpot per battle
Kadar's comment on Chemist Pots gave me a new perspective, i think i'll have to go for No Pots/Healing items whatsoever, even for Chemists.
Converters would be fine Just 1 Per Battle.
Also 1 aspd pot per Battle, maybe 2 Max.
No item Buff, it just doesnt sound right for a Fair PvP battle.
As for the Time, 3 Minutes OR untill the GM thinks it is correct. Like, if a fight looks really close but a little long, the GM/Host can either decide it a Stale Mate and end the match, or extend it a little so they finish.