Which one should i trust?
Rating movesets from GamePress or IVFly? (formerly ivstats).
Answers
Trust your own reasoning. Try to understand with which methods those ratings are made, look if this would match to your playing style.
For example, i do not trust pokemon rating (0-10) on gampress at all, it seems to be randomly adjusted CP-values. There is no explaination what this rating should mean.
Moveset Rating on gamepress seems to concider circle damage against a neutral defender, what not always makes sense. - Sometimes, I d not need damage against neutral defender, e.g. Venusaur with Sludge-Bomb is valued "B" on attack, is useless for me.
I second the trust your own reasoning. That is also the reason I trust this site. I have found that this site most accurately represents my experience, for the most part.
They do extensive testing that take a lot of things into consideration, some that fit the meta, others not so much. But your Venusaur example is similar to the bullet seed vs es Eggy debate...against Vaporeon, they are basically equal. Lets look at Venusaur vs Vaporeon...
Venusaur is a posion type, which means SLB gets STAB. SLB does 140 damage for a full bar of energy, Petal Blizzard does 110. Against Vaporeon, PB is SE, which does 137.5 damage.
For 1 bar of energy against Vaporeon:
PB-137.5 damage
SLB-140 damage
Basically they do the same damage. What does pokebattler say?
https://www.pokebattler.com/fights/attackers/VENUSAUR/quickMoves/RAZOR_LEAF_FAST/cinMoves/PETAL_BLIZZARD/cp/2200/defenders/VAPOREON/quickMoves/WATER_GUN_FAST/cinMoves/AQUA_TAIL/cp/2900/strategies/DODGE_SPECIALS/DEFENSE?includeDetails=true
https://www.pokebattler.com/fights/attackers/VENUSAUR/quickMoves/RAZOR_LEAF_FAST/cinMoves/SLUDGE_BOMB/cp/2200/defenders/VAPOREON/quickMoves/WATER_GUN_FAST/cinMoves/AQUA_TAIL/cp/2900/strategies/DODGE_SPECIALS/DEFENSE?includeDetails=true
Using the same modifiers SLB wins against a 2900 cp Vaporeon in 32.4 seconds, compared to PB winning in 33 seconds. This tells us that they are essentially the same, and what do ya know, gamepress has them ranked the same.
This just goes to show that poison moves on Venusaur are just as lethal, just not nearly as sexy as double grass moves. Obviously SoB out-classes both of the other moves tho.
I think that would come down to your attackers. If you are looking for another attacker that resists water, he would be good. The problem is vw isn't good on defense, so maybe wait and see how the gym update goes. I have a rl/sb Venusaur, which I would max, except the IVs are less than 82, and with the current cp system, that is just a little too low for the gyms around here I think.
There are also Gameinfo and Tripledex and others.
These websites are to inform but not always a definitive source. Each website judges movesets in diff manners. For example, Gameinfo is just pure DPS when it judges its movesets, not considering other factors. So if you want to judge movesets by pure DPS, then use that websites' info.