Cryogonal is an Ice-type Pokémon from the Unova region and for a limited time during raids, you have the option of catching it in Pokémon Go. While it's not a five-star raid or legendary Pokémon, it remains a tough opponent. Taking it down will be a bit of a challenge, and with the correct Pokémon and strategies at your disposal, you may be able to take it out on your own.
Cryogonal is purely an Ice-type Pokémon, which makes it weak to the moves of Fighting, Fire, Rock, and Steel-type Pokémon. It's ice-resistant only, which means that if you have several Fighting and Fire-type combinations available, you should do it reasonably well. However, you can always use a Rock-type Pokémon to counter its powerful attacks.
Pokémon compete for the Cryogonal
Some of the best choices available for fighting this Pokémon include Metagross, Blaziken, and Conkeldurr.
Metagross is a Steel and Psychic-type Pokémon. While you don't want to lean on any of Metagross's Psychic-type moves, it's an excellent Steel-type choice, especially if you have the charge move meteor mash. The fast attack for Pokémon can vary, but the bullet punch is probably the best option. You can place Metagross anywhere in your lineup and do exceptionally well against the Cryogonal.
The next option is Blaziken, the Fighting and Fire-type Pokémon. It is an exceptionally strong Pokémon but leans more towards the offensive mentality. It's not a defensive Pokémon, so you'll need decently robust alternate options alongside Blaziken. You want to have one that can counter and ignite, cast fire and burn, or counter and burn. All of these are relatively strong options when fighting Cryogonal.
Another choice you can go to is Conkeldurr, a Fighting-type Pokémon. Just like Blaziken, it has an exceptionally high attack volume, with reasonably low defense, but is an ideal Pokémon for raiding. Another good thing is that it is resistant to Dark-type attacks, and some players have reported fighting a Cryogonal in raids with night cuts, which would be a great way to counter that attack if you were to face one. It's subtle, though. You want to use one that knows counter and dynamic punch or counter and focus blast.
There is a large variety of different Pokémon to use against the Cryogonal in addition to the three mentioned above. You can always use Darmanitan, Entei, Heatran, Moltres, Reshiram, Machamp, Chandelure, Terrakion, Charizard, Flareon, Arcanine and many more.
Some players are curious if they can play Crygonal alone and the answer varies. Mostly higher tier Pokémon Go players have reported being able to take down a Cryogonal, but it's possible. If you stick to weak Pokémon with Cryogonal, you should do exceptionally well against it.