Dewgong @ Chople Berry/Leftovers
Ability: Thick Fat
Level: 50
EVs: 252 HP / 96 SpA / 156 SpD
Calm Nature
IVs: 0 Atk
- Perish Song
- Ice Beam
- Surf/Hydro Pump
- Protect/Toxic
I've put a variety of options here since it's not just about what Dewgong can do vs. Suicune, but what utility it can provide to the rest of the team. Chople is great for eating a hit from Mega Blaziken. If one runs pump, they can eat a hjk from max adamant and guaranteed OHKO non-bulky Mega-Blaziken after rocks if running pump though it does sacrifice accuracy. This is not including the Protect mindgames. It guaranteed takes a double edge from jolly mence and has high chance to OHKO non-bulky mence with ice beam, which is guaranteed with blizzard but not worth the accuracy drop. You can run leftovers over chople if you aren't concerned with strong fighting types like mega luc/mega blaziken.
Dewgong mishes Suicune in the 1v1, perish song consistently forces Suicune out when it decides it wants to do its silly shenanigans. Even at +2, Hydro Vortex from max spa suicune bounces off the GOAT that is Dewgong.
+2 252 SpA Suicune Hydro Vortex (160 BP) vs. 252 HP / 96+ SpD Dewgong: 92-108 (46.7 - 54.8%)
As for scald:
252 SpA Suicune Scald vs. 252 HP / 96+ SpD Dewgong: 23-27 (11.6 - 13.7%) -- possibly the worst move ever
Just read what the calc says.
Ice beam can of course freeze. Dewgong cannot be haxed by suicune ice beam due to having that ice type.
Toxic can be ran over protect, which gives a better matchup vs. more bulky mons such as P2 and suicune without rest if they are able to keep switching around. Protect is better for pure perish trapping.
Literally the only thing Suicune can do against a full health T H I C C fat dewgong is hope they have roar so they don't have to face this monster.