You might recognize Lokhlass from the animated Pokemon show. It first appeared during Pokémon Gold and Silver, and the large creature is making a return in Pokémon Sword and Shield.
Water and Ice type Pokemon are hard to miss as you can see them floating along the water's edge in the Wild Area. Unfortunately, you need to get the Rotom Bicycle upgrade to cross the water after battling the sixth animator and lead the water race. You cannot catch it by throwing your fishing rod into the water. So you can see a few floating around, but you can't get hold of them.
When you receive the Rotom Bicycle Upgrade, you can find it throughout the Wild Area, in Water Areas. Jump into the water and climb on it. Since it's a Water and Ice type Pokemon, you want to be careful when using Grass and Electric types.
The Lake of Outrage isn't the only place you encounter Lokhlass. You should check every large lake in the wilderness to increase your chances of encountering a Lokhlass. They appear quite often, so you should be adding one to your collection in no time.
Lokhlass has a Gigantamax shape.