Ok, but none of those guys can do jack if they get put to sleep or face a substitute on the switch in. Not to mention super effective hidden powers (including hidden power psychic) are always a possibility.
There are 3 common Venasuar sets. Scarf, Specs, and SubSeed. Pending on what it leads off with allows you to assess guesstimate the set and move from there. I really dislike it when people assume to much from a poke'. I give it far to mch credit than it is capable of. This is only a
Example: Garchomp always seems to be carrying Yache/ Scarf/ SD/ Fire Fang/Blast when you make a arguement against it. Atleast that is how I few it and it really seems to make the situation worse than what it is.
However, this is infact about Vena so here is a hypathetical situation.. for the sake of arguement
Blue led with Electrode and KO'd
Red's Ninetails right off the bat.
Blue send in Blastoise and
Red sends in
Golem and here we go..
Red sends out Venasaur.
Blastoise uses Surf...
Venasuar lost 10% HP.
Blastoise's Leftovers restored some HP.
[End of Turn]
Just from here you can easily assess the situation. No lefties tell's you there is a very High Chance that it is Scarf/ Specs.
Blue sends out Swalot.
Venasaur uses Energy Ball.
Swalot lost 20% Hp.
Swalot's Black Sludge restored some HP.
[End of turn]
Venasuar led off with Energy Ball so that should tell you that, 1) It is most likely not Scarfed since it did not lead off with Sleep Powder and 2) Damage to Vileplume was rather high so your best guess is Specs.
If that is the case Venasaur is more than likely carrying Hidden Power whish would be Hp Hp Ice or Hp Fire. Since Smogon anaylisis says he should have Hp Ice then that would be your best assumption.
This "logic" can be used for other pokes as well.