This post shows another way to counter this "undefeatable" strategy. Switching constantly between two regenerators. You can add that to the long list of usable thing that also deal well with swaggplay such as taunt, strong priority, toxic spikes, sylveon, blissey, mandibuzz, unaware cleafable, defensive pokes, smartly switching a magic guard pokemon on a predicted t-wave, etc, etc)
But nevermind, I know you guys are going to ignore all this and keep saying that this strategy is OP because the only "real" counter is numel.
Sinning, want to see a game of prankster that requires skill, see
this.
Congratulations on missing the point entirely. The point is not that prankster swagger has not been banned before. The point is that a gimmicky, annoying but not overpowered strategy has never been banned before. If smogon bans this, it basically means that they will ban anything as long as a big amount of people complain about it, regardless of whether the srategy is OP or not.