Howdy! Big fan! I got pretty high up with this BSS team I built on Champions which uses Future Sight M. Delphox and Life Orb Roserade.
I hope you like it and maybe even try it out in a video!
M. Delphox (aka Gandelph) is a really strong breaker that can pick up KOs on potential sash or setup mons using Future sight, with Substitute to outplay
M. Golisopod + Kingambit Sucker punch (M. Goli always KOs with First impression tho), Overheat to hit as hard as possible, and Psyshock as a secondary psychic stab.
Rocky helmet Corviknight is your switch in to most physical attackers and your hazard removal, with Bulk up to beat M. Salamence if it tries to setup on you and potential sweep.
Primarina bulky all around and hits big threats of the metagame hard. It has enough investment to live a non-boosted Double edge from M. Salamence, and also a +2 Flash cannon from M. Lucario Z. It also has Haze to beat Baton pass + Stored power teams or M. Clefable setup in general.
Scarf Garchomp picks up easy KOs on those who don't scout for it. Garchomp also acts as a switch in for Cinderace which Corviknight struggles with. Also most M. Salamence run adamant or not enough speed investment, so Garchomp can still out speed even after a Dragon dance.
Life Orb Roserade is a really strong anti-meta pick. Its purpose here is to beat opposing Primarinas, Milotics, Rotom-Wash, etc. A lot of players underestimate it and will switch out to, for example, their Salamence only to take ~70%. I also have Shadow ball on it to it isn't completely walled by Gholdengo.
Lastly, I have M. Lopunny which dominates match ups into Focus sash Baxcalibur, M. Banette teams in general, Mimikyu, and Umbreon, all of which M. Delphox can struggle against.
I think this team has a lot of potential, which is why I wanted to share it before the regulation ends. Get better soon!
https://replay.pokemonshowdown.com/gen9nationaldex-2691260955-frdhxm5vedvt5s778hc6tg31cs6mg5kpw
https://replay.pokemonshowdown.com/gen9nationaldex-2691259425-05xuac1l4cidrsq1gfqghnrkmj0d77fpw
Just a few Garde MUs into stally structures.