There's a lot of information you're missing and misunderstanding. Short answer is that moveset doesn't matter since it changes when you evolve.
Long answer: You need to calculate what level the Venonats are first, and from that calculate which has better IVs. Also the moves they have, even if you weren't going to evolve them, have different attack speeds so the damage per second can vary. Also, powering up in general is a waste of candies because evolving gives you experience and requires candies, and the main limiter on how strong your Pokémon can be is what trainer level you are, so you probably shouldn't power anything up in the first place.
Check our guide on Pokémon Stats - Advanced for more info.
