I saw the winning lists from the Commander 1v1 league, and they were mostly the same deck: mono-blue Legacy. I made a mono-blue deck with a little more of the variety I like, and also at a much more casual power level.
I played against a Mirri the Cursed deck.
Here, I send Mirri back to my opponent's hand.
Dissipation Field kept my opponent at bay.
My opponent placed two enchantments on Thassa.
I returned Thassa to my hand and made a few more plays before my opponent gave up. Based on the league results, and until the banlist is expanded to weaken Blue, the only good decks that can be played in this format will be mono-blue, or heavy on blue.