Dada is literally nothing. Art that fills the space of everything there isn't a word for yet. My hope is that everyone who practices the philosophy honestly would agree with me. I know for a fact that not all of them do. But they're still Dadaists.
There is no litmus test. Everyone who has thoughts on art is welcome. Anyone who disagrees with a Dadaist is a Dadaist. And then Dada will creep in and slowly infect their little minds until everyone is dancing naked on street corners singing songs in made-up languages.
The only caveat is that Dada represents a kind of radical inclusion, and you have to practice it to be it.