Wong Yerk See's formations and Lee Mok Sau's poisonous projectiles are key elements of their standard attacks and thus, are fair game. I would find it strange if they *didn't* use these capabilities (for Lee Mok Sau, especially, the poison projectiles are almost her default attack). As for the Divine Condor and Gwok Jing's twin condors, neither ones were essential parts of Yeung Gor's and Gwok Jing's normal attacks. Au Yeung Hak's use of venomous critters was more analogous to the first two (Wong and Lee): they were essential elements of his normal attacks. It would be strange to see Au Yeung Hak *not* use these if they're at hand.
Well I believe when someone compared A vs B mostly based on their pure "skills" except the they use venomous skills like You Tanzhi or Ding Chunqiu since they come from "evil sect" so if we agree using poisons or snakes or anything against each other why we didn't allowed Yang Guo for using sword/weapon against Guo Jing maybe why only Ouyang Ke have such of "wildcard"..