Most popular Pokémon in 1v1.
What do you mean by how viable it is? It is S-rank in viability rankings! here is a statement from its Scarf set:
Urshifu-S's job will mainly be to lure in slower Pokemon and use its STAB moves to deal with them. Against stall Pokemon like non-Charm Chansey and Galarian Corsola, Urshifu-S should use Fling turn one to get rid of its Choice Scarf so it can start setting up on them with Bulk Up and break through with Wicked Blow. Against Crustle, use Fling turn one, as it is most likely carrying Counter, and then use Bulk Up until Urshifu-S reaches +2 to knock it out with Wicked Blow. Close Combat is notable for defeating most Porygon-Z variants; however, defensive Chople Berry variants can tank a Close Combat and knock out Urshifu-S with Hyper Beam.
Also
Unseen Fist is a unique ability that allows Urshifu-S to combat Torment and Protect users like Skarmory and Steelix.
As you can see its very viable. Hope I Helped! Source
