Lapras vs Cloyster vs Articuno
Which is the best ice type "Dragonite slayer"?
All 3 have access to the ice fast move Frost Breath.
Lapras has a legacy ice fast move Ice Shard, but Cloyster can still learn Ice Shard.
Lapras has the lowest attack stat, but decent defence, and the highest stamina. It has one of the best bulk in the game. Like Articuno, it lacks the best ice charge move, Avalanche.
Cloyster has 6 lower attack than Articuno, but due to access to Avalanche, which is a faster Ice Beam, it is on par with Articuno. Cloyster also has the highest defence stat, but the lowest stamina. It has the least bulk, because of how bulk is calculated.
Articuno edges out Cloyster slightly in attack stat, but is on par with Cloyster as it can't learn Avalanche. Its bulk is on par with Lapras. Also, it is weak to Steel Wing.
Answers
I've always been confused when people talk about Cloyster's high defense and not losing a lot of HP as though that is a good thing. Having lower defense and higher HP such that you lose the same proportion of HP with each hit would be better for energy gain.
The main thing going for Cloyster has always been it is "potion efficient" for people that are low on potions. But one max potion/revive will heal Cloyster and Lapras equally well.
I guess Jynx fails to make the conversation because she is too frail? Hmmm...I'm sitting on a 100% Jynx with Frost Breath/Avalanche at L20. Can't decide whether I should power her up to L30 or go with my TM'd double Ice 96% Lapras or my middling 82% IV Articuno. I'm totally lacking strong Ice mon - only have one good Piloswine and one decent enough Cloyster - both at L30.