I'd like to note that I'm glad that the discussion about Rillaboom seems to be well conducted and handled by
Pinkacross and
Finchinator
Anyway, to the point: Urshifu-RS
This pokemon has markedly risen in usage, without much notice. Kyurem, Lele, Scizor, etc have all been rising threats as of late, and have been discussed at length here, but Urshifu-RS seems to have been missed. It is #13 in the usage stats of March, which (for comparison) is between Lele and Zapdos, and a few spots ahead of Tornadus-T.
In this post, I will try to explain this metagame shift to the best of my ability. Then, I will explain how you might use this pokemon, and finally I'll give my favorite team to use it on at the moment (which brought me to top 500 personally, despite many fairly obvious flaws).
WHY?
First, let's see what has changed in the metagame. The removal of Cinderace didn't really impact Urshifu-RS, but the removal of Magearna was a mild improvement for it (one less pokemon that kinda beat it). However, unlike many other pokemon such as Slowking, Scizor, or Kyurem, this is not sufficient to explain Urshifu-RS's rise. For that, we have to look more closely at the effect that those bans had on the overall metagame. They meant that less pokemon were running rocky helmet (Yay!), Slowbro lost popularity (Yay!), and that Slowking rose to prominence as a great bulky water esp for offensive teams. If you look at this, and then look at Urshifu-RS, it appreciated all 3 of these changes. Slowking is far more breakable than slowbro, nearly being 2hko'd by both of Urshifu-RS's stabs (btw- that still doesn't make sense to my brain, why is this doing that much). In contrast, Slowbro (esp with rocky helmet) was as good a counter to Urshifu-RS as you could ask for (although it takes about 40% from U-Turn). Rocky Helmet being used less helps it's longevity substantially. Other bulky waters are not really a problem for it either- Fini for instance can only come in a few times before being chipped to the point of uselessness. Toxapex is the hardest to deal with, but with Future Sight support it's still quite easy.
As for other meta changes, Urshifu-RS usually didn't mind them that much- for instance Kyurem and Lele's increase in popularity is whatever, fine. Scizor becoming more popular was if anything a positive change, as that pokemon can never really take hits from it.
HOW?
Urshifu-RS very much appreciates Future Sight and Spikes support. I would even go so far to say that Future Sight is almost required for it to be successful, as otherwise Pex is a large problem. Teleport support with the Future Sight support is very useful, and as such Slowbro and Slowking are the best partners there. One of my favorite cores featuring it is Skarmory+Slowking+Urshifu-RS, which provides both spikes and Future Sight support for it. Skarmory appreciates the two water types to help against fire types, while Slowking and Urshifu appreciate Skarmory dealing with the grasses that annoy them. Note that if you go down this path you will want a solid way of dealing with various electric types.
EXAMPLE?
(importable linked)
Note that this team struggles against dragapult and electric types. It also has no hazard removal, but I think that's fine considering how little the team cares about hazards and that I have spikes. If wished, you can replace Zeraora with scarf Lando.
Hopefully this helps yall understand why Urshifu-RS is becoming more popular as of late, and helps you build your own teams featuring it. Have a good day!