Cloyster - Power it Up?

CP or LVL of your cloyster?

I tried with a similar 82% Cloyster that I evolved from a wild-caught shellder already quite well powered up (level 28, cp 1607). It definitely does some damage fast, but to be honest the HP (80) is so low that its tough to avoid taking too much damage in return, even with good dodges. Miss one dodge and its over. Considering that even if you could waste the dust to power it right up to level 40 it will only get cp 2000 it still wouldn't be a match for my 2000cp Lapras with IS/DP even: with care I can take down 2 dragonites at 2600-3000 with the Lapras and no revive. I quite like IS despite the slowness - its one of those fire once and dodge moves (like razor leaf on my Victreebell) which makes the process nice and progressive/predictable rather than explosive destruction. And since DP isn't optimal as a charge, it gives you plenty of time to watch and think and wait for the opponent to use their charge move. So I would save the dust and put it on one of your other Laprases even with suboptimal moves.

Without giving any attention to your particular Cloyster: I have a feeling there soon will be a need to have multiple strong ice attackers on hand. The reason is the tendency of Dragonites to push other types out of the gyms. With their high CP they place atop everything else, thus accumulating over time as the lower levels get stripped. Just yesterday I encountered a level 10 gym, which had six Dragonites in the top positions. Such a monoculture actually weakens a gym, as a specialized attacker goes from one helpless victim to the next.

I wouldn't.

I mean, I was in the same situation and I did.

Do I use him? Yeah. But I use Dewgong more. And when I do use Cloyster, I also use the one I evolved from a level 30 Shellder with only 60% IV's that didn't cost me any dust..so the benefit of powering up the high IV one has been minimal.