Lapras and Snorlax low Iv

Its kinda hard but for me I would power up that Lapras if u don't think u will get another one anytime soon as moveset>ivs and lapras already has monster stats. Frost breath/ blizzard is also the best so ivs wont really matter. For snorlax both are ideal for attacking but if u feel hyper beams better for attacking then power that up

The final Snorlax will make a solid gym defender with that moveset.

All your mons are badass. I'd power them up if I have got enough candies and stardust.

I wouldnt power any of them. No defensive moveset.
Anyway you dont have enough candies to power them up to lvl30+ so wait to get enough candies then ask the question again with your new Lapras/Snorlax

They are all usefull as attackers but dont waste candies

Sorry, but I can't see any utility powering up attacking pokemons... That Lapras has a perfect attack moveset and can take down 3-4 3K CP Dragonites in a row as is. When it comes to train friendly gyms the rule about your attacker CP is the less the better.
So: why upgrading?
Bother about IV and full powering up only for gym defenders.

Even the lowest IV snorlax and lapras is better than other pokemons. Consider this, I'd rather have 0 IV lapras than 100% dewgong or cloyster.

First of all, in general, defending Pokémon are more worthy to power up than attacking Pokémon. Lick is a very weak defending move so for that reason I wouldn't power up any of the Snorlaxes. For attacking they will already do just fine at that CP range.

The Lapras does have quite low IV and the moveset is not optimal for defending. So by using the same logic I wouldn't power that one up either. It's already great at attacking even with that CP and does not really require powering up.

You have 3 really nice Pokémon there and none of them even requires powering up. If I were you I would just keep that as they are and save the candy for better defending Pokémon.

The best "defensive moveset" is a high CP. Sure someone might struggle more to take down your pokemon, but an ideal defensive moveset will always be outclassed by an extra potion or two. And unless every other person in the gym also put a pokemon with the ideal defensive moveset, the difference is negligible. However, being the gym leader or somewhere near the top will insure that your pokemon holds the gym longer, unless someone with plenty of time on their hands decides to take down the gym, in which case, moveset wouldn't matter regardless.

So if I understand everyone correctly then my Lapras that has 51% IV's 1991cp, (1-7-15) and 50 candies. with Ice Shard & Ice Beam best defense moves i should power it up to level 30.