This will resolve based on the results of /Gabrielle/which-states-will-be-won-by-the-dem-540e6b923486 . Individual answers will resolve as they are able to.

Flip is defined as voting differently than it did in the 2020 result. D ->R, R -> D, and also R -> I and D -> I count as flips. (I have not yet picked an underlying market for the question of independent results; I will update this description when I do. The intent is to have this be a fully derivative market long before the election rolls around.)

I haven't added the full set of possible counts; I didn't think it needed them. If the higher counts aren't close together in probability I'll add the missing ones. I'll also be happy to add if someone requests it.

This is the same set of states as this market:
/EvanDaniel/close-states-how-many-of-13-vote-de

And the same set of conditions for what counts as a "flip" as this market:
/EvanDaniel/how-many-states-districts-flip-in-t

EDIT: for the edge case of states voting third parties (D->I or R->I flips), I will use the official Manifold Politics markets, which include I as an outcome option. This market and its friends:
/ManifoldPolitics/which-party-will-win-the-us-preside-c1307cf9f69a