What I'm expecting: "There's obviously voter fraud in Pennsylvania, we had Xmillion people sign the petition and only Xmillion votes!!"

If Trump [or someone else] makes the claim and Elon uncritically shares it on X, that will also suffice. If he mentions voter fraud, i.e. "Trump claims there is voter fraud in Pennsylvania", that is insufficient. Someone needs to cite the super PAC numbers vs voter numbers.

If Elon reposts a list of 50 fraud claims and this is one of them, it may not count. The key spirit of the market here is: It needs to be clear that Elon read this exact claim and is uncritically amplifying it, or explicitly endorsing it.

Not conditional on Trump winning/losing the state.

I have been asked not to trade, so I won't!