Let's consider for a moment all of the ways suggested to "counter" or "beat" SwaggPlay.
Magic Bounce: There are three fully-evolved users of Magic Bounce: Espeon, Xatu, and Mega Absol. Mega Absol is outclassed by a slew of other Dark-types, AND it requires a Mega slot to use. In general, your team will be better off with Tyranitar or Bisharp or even Crawdaunt than Mega Absol, since they all hit just as hard or harder, have equal or better bulk, and don't require a Mega slot to use. Next, has anyone ever used Xatu in XY OU to reasonable success? I haven't used it myself, but I can't see it being too useful when Rotom-W, Aegislash, Tyranitar, Scizor, Greninja, and even Talonflame completely destroy it. Finally, sure, Espeon is more viable than the other two. But its defenses are mediocre at best (barely better than Mega Absol, in fact), and everything in the above list sans Rotom-W eats it alive as easily as Xatu. Essentially, Magic Bounce is a spectacular ability gifted to three otherwise underwhelming Pokemon. Last generation, Magic Bounce was useful to reflect hazards, but Defog has made hazard-clearing easier than ever before, rendering Magic Bounce almost entirely unnecessary.
CONCLUSION: Magic Bounce is an excellent response to SwaggPlay, but its users are rendered so obsolete by the current metagame that SwaggPlay itself and BP chains are basically the only reasons to even consider running one.
Magic Coat: The following Pokemon in the top 100 in usage last month learn Magic Coat: Porygon2, Absol, Clefable, Alakazam, Tentacruel, Slowbro, Magnezone, Starmie, Togekiss, Espeon, Celebi, Gardevoir, Sableye, Medicham, Latias, Latios, Jirachi, Deoxys-S, Deoxys-D, Reuniclus, Jellicent, Genesect (irrelevant). Seems like a pretty big list, right? Except that Porygon2 needs BoltBeam, Toxic, and Recover. Clefable needs a recovery move and either CM/Stored Power/coverage or Aromatherapy/other cleric-type moves. Alakazam needs coverage, Tentacruel needs TSpikes/Rapid Spin/Scald/Ice Beam, Slowbro needs either coverage or Slack Off/IB/Scald/TWave, Magnezone needs TBolt/HP/Sub/Magnet Rise or something, Starmie needs coverage, Togekiss needs coverage or NP/Roost/TWave, Gardevoir needs coverage, etc. The only Pokemon on this list that even have a spare slot in which to run Magic Coat are Magnezone, Deoxys-S, and Deoxys-D. Deoxys-S is undoubtedly the best of the lot, and its lead set is basically meant to die, so it's not going to be much help stalling out SwaggPlayers. Magnezone could really use Charge Beam or Flash Cannon instead, since Substitute takes care of most of its problems anyway. This leaves the list of viable Magic Coat users at: Deoxys-D.
CONCLUSION: Magic Coat is a good move, but there isn't enough of a reason to use it on anything but Deoxys-D except to specifically beat SwaggPlay. Deoxys-D is most certainly not an optimal choice for every team.
Lum Berry: Yes, there are quite a few OU setup sweepers that already run a Lum Berry, most notably Dragonite. However, Lum Berry is good for exactly one instance of status, meaning that, hypothetically, if Dragonite and, say, Klefki switched in on each other simultaneously, DNite would have the choice to Dragon Dance or Earthquake. Dragon Dance is a terrible idea, since Klefki will undoubtedly use a status move, thereby by leaving DNite vulnerable to status on the next turn. Earthquake is also a decent option, but it will not OHKO, and Klefki simply TWave to break Lum and then follow it up with Swagger. This same reasoning holds for any and all other users of Lum Berry, with the sole exception of Trevenant (who, by the way, is weak to Foul Play).
CONCLUSION: Lum Berry does not counter/beat SwaggPlay, although it can halt its progress for exactly one turn of a match.
Prankster Taunt: Definitely a solid option, and probably the most commonly usable one on this list. However, keep in mind that the fastest user of Prankster Taunt is Whimsicott, who is undoubtedly nonviable (even on SwaggPlay teams, strangely), and the second-fastest is Liepard, which is seen in OU primarily as a SwaggPlayer. Liepard can outspeed Thundurus and Taunt it first or simply set up a Substitute on it, allowing it two free Foul Plays. The other Prankster Taunters (Sableye, Mega Banette, Tornadus, and other less-useful 'mons) are also outsped by Prankster Liepard, meaning they can deal with it about as well as Pokemon without Prankster. (Also, notably, Klefki outspeeds Sableye, the second-most common Prankster user, by a lot and also 4x resists Foul Play, Sableye's most common attacking move.)
CONCLUSION: Prankster Taunt completely shuts down SwaggPlay, but all of its viable users are slower than Liepard, a SwaggPlay staple which also has access to Taunt if need be.
Own Tempo: Here is a list of all the Pokemon in the Top 200 in OU usage last month with access to Own Tempo: Slowbro, Slowking, Smeargle, Ludicolo, Lilligant, Avalugg. Slowbro and Slowking need Regenerator to perform their primary functions, Smeargle never knows any attacking moves and therefore cannot beat SwaggPlay, and Ludicolo is outclassed by almost every other FE Water-type unless it uses Swift Swim on a Rain team. This leaves Lilligant and Avalugg as viable users of this ability. Lilligant hates paralysis, as it renders it incapable of sweeping (assuming, of course, that you use it over something like Volcarona, which is generally better), and Avalugg is SR-weak and can be killed by the majority of common special attackers without difficulty.
CONCLUSION: Of the three Pokemon who can afford to run Own Tempo as their ability, one never carries attacking moves, one is outclassed very badly and is ruined by paralysis, and the third is badly equipped for OU.
Substitute: What even runs Substitute nowadays besides Kyurem-B, Breloom, and Magnezone?
CONCLUSION: Substitute also beats SwaggPlay, but it is as difficult to fit into a moveset as Magic Coat.
Safeguard: Name a single Pokemon in the top 250 in OU usage in January for which Safeguard is one of its top six move options. I dare you.
CONCLUSION: Safeguard is too niche to be usable in OU.
Numel: Only suggested as a joke, I'm sure.
CONCLUSION: Use Simple Stockpile Numel in LC.
Switching: This is an intriguing suggestion, but I think it misses the point of what beating SwaggPlay means. Suppose you've set up a Volcarona to +6/+6/+6 due to your SwaggPlaying opponent's incompetence. They send in Liepard on you, and you confidently hit Bug Buzz, knowing it will easily OHKO, even through Substitute. Liepard, thanks to Prankster, moves before your Volcarona and uses Swagger. Suddenly, your perfectly set-to-sweep sweeper has a 45% chance of doing damage to itself instead of killing Liepard. If it kills Liepard, great, in comes Sableye, which can now use TWave instead because you're already confused. If it hits itself, however, you might want to deal with your status condition by switching. BUT WAIT. If you switch, Volcarona loses those boosts that you've accumulated over six turns. Liepard has successfully UNDONE 6 TURNS OF EFFORT with a SINGLE MOVE that you COULD DO NOTHING ABOUT. SwaggPlay serves more purposes than haxing teams to death: A single SwaggPlayer on an otherwise average team can, with 90% probability, PHAZE A FULLY SET-UP SWEEPER before it has a chance to move. And then, by switching, you've left yourself vulnerable to SwaggPlay's traditional function: haxing you to death. SwaggPlay, in essence, acts a lot like Prankster Circle Throw Riolu from BW OU: incredibly gimmicky and requiring a lot of luck to pull off, but nearly impossible to stop once it gets going. And, unlike Prankster Circle Throw Riolu, SwaggPlay 1) doesn't require the user to take a hit first, 2) isn't completely ruined by priority, and 3) can work on Ghost-types.
CONCLUSION: Take Prankster Circle Throw Riolu. Now put 6 of them on a team, give them the Attack stats of your normal team, and make Circle Throw increased priority to begin with. You have now approximated a SwaggPlay team.
OVERALL CONCLUSION: There are certainly ways to beat SwaggPlay. In fact, there are many ways to beat SwaggPlay; the problem is that all of them seriously hinder the ability of the opposing player to win consistently, regardless of skill. SwaggPlay stops sweeps while simultaneously starting its own; SwaggPlay requires using otherwise useless Pokemon/items/moves to counter it; SwaggPlay consistently places the outcomes of matches into the hands of fate. That is what differentiates SwaggPlay from Jirachi or Ice Beam or Quick Claw: it can consistently render skill obsolete in determining the outcome of a match. For this reason, I support banning Swagger + Prankster. Swagger without Prankster allows it to actually be beaten consistently by priority or, heck, Lum Berries. Other confusion moves don't allow for the compounding damage that Swagger does, meaning physical walls can actually do their job properly. It is only the removal of Speed from the equation that allows SwaggPlay to be as effective as it is. Without Prankster, SwaggPlay can no longer reverse sweeps, hax faster Pokemon, or be un-Tauntable, which are three of its most gamebreaking characteristics.