Your opponent can easily react to evasion through the use of it's counters. This does not make the strategy one bit less unfair and uncompetitive than it is. Swag Play is less fair than evasion, given that the same arguments for, and against, both cases can be argued through literally the same points, yet evasion has more easily accessible, viable counters than Swag Play.
I don't particularly care if it's banned or not. I just have a problem when rules are not uniform. If we ban evasion, we ban this. Unless you can prove that Swag Play is somehow different, while also being more fair than evasion, there is no argument for keeping it around.
The difference between evasion and Swag Play is this. Evasion has easily accessible counters in the form of perfect accuracy moves (on pokemon who are viable, ie are decent enough to not be dead weight against other teams) and phazing. These things do not counter swag play, due to swag play always moving first, which immediately adds an element of chance to each of your opponent's turns before your opponent is allowed to respond, and Swag Play also being an offensive strategy. Minimize and Double Team are only defensive, and do not remove the possibility of the opponent interacting, or countering, the strategy. Swag Play is basically evasion, that can 1HKO or 2HKO any pokemon threatening to KO the user, while also removing the opponent's ability to play the game.
This is clearly worse than evasion, and if we feel the need to keep the evasion clause, we must additionally ban this strategy.