Dewgong vs. lapras vs. Cloyster

Dewgong is very weak after the CP changes, so I would focus on getting a Cloyster since Lapras is so hard to find. Cloyster has low HP but very high Defense, which compensates for the low HP. His attack is the same strength as Lapras. Jynx with FB and Ice Punch is another option if you dodge a lot.

Depends on how you are using it. If you just need an ice pokemon for training, Dewgong with Frost Breath+Blizzard is still perfectly usable.

Is this a question or what?