Brecht is an avant-garde writer. The Verfremdungseffekt is derived from Shklovsky, a Russian formalist. Distancing techniques are essentially meta-theatrical, like the breaking of the 4th wall. Of course, anti-realist techniques are not inherently avant-garde, in the sense that other forms of theater (from Asia, for example), are not avant-garde per se. Placed in a European context, however, they become anti-naturalistic.
Distancing that doesn't serve a didactic function is not Brechtian. In other words, you could use those techniques simply for their entertainment or surprise value.
So you need three things: a set of techniques, a cultural context where those techniques would be seen as distancing (not simply the normal practice of a non-naturalistic theater) and a social intent.
Lorca uses metatheater in the work formerly known as "Comedia sin título." I saw a version that combined this play with a new second act, full of Lorquian kitsch. Grrrr.