Aside from pinning down "antifa's" core beliefs, insofar as that is possible, I think we can all agree that the way "antifa" gets characterized by conservatives is just really stupid. I doubt they could even agree on a set of core beliefs. They are just college kids that like to spray paint graffiti on the side of a Starbucks, and that is the extent of their revolution. Conservatives just need some kind of amorphous boogeyman to pose as an enemy, and since it isn't as acceptable to use Jews for that purpose anymore, they are pointing to these activist kids who are dressed in black and have a vaguely leftist cause since not much is known about them.
If there really was a group that was well-organized with a well-defined mission to oppose fascism, I would certainly be interested in joining, but no such group exists, in the USA at least.