Rank

it says im grandmaster but its showing me that im arceus when i go check?

The UI isn't ideal, it hasn't been fully optimised for the new percentage-based ranking system. What it's trying to tell you is that you have claimed the Arceus rank reward and that your next goal "should be" Complete. You have, however, dipped below the threshold for Arceus rank due to the new releases today. I will be looking into improving the UI, but this is not a bug.