Gonna give it to you straight and practically the only way anyone is able to beat Perish Trap is by going for hard reads or basically out predicting your opponent. If you see Gengar with any of the following Pokemon: Scrafty, Gothitelle, Azumarill, Arcanine, Politoed, Dewgong, Amoonguss, Liepard, Whimsicott, and even Kangaskhan then it should be a good hint that the opponent is running Perish Trap. Now to be honest, most defensive teams tend to not have any form of answers when it comes to Perish Trap aside from running a Ghost type like Aegislash, Gengar, or even Sableye. Its a very difficult match up I'd admit , but not unbeatable.
1) Bring Your Best Hyper Offensive Cores and maybe One Slow Pokemon: Basically just have 2-3 Pokemon that can go against Mega Gengar and can OHKO him immediately. Now be weary that Mega Gengar can Protect and for for Disable just to shut down any of your attacks so go after its partner first so you can get some offensive pressure going. The reason why I stress this point so much is once Perish Trap is reduced to 3 Pokemon, it becomes less effective as the opponent may have to sack or let their Pokemon go down. It might be worth noting that Perish Song lets the slowest Pokemon faint (who ever faints last wins in a 2v2) so have something like an Amoonguss or Ferrothorn as the last Pokemon since Perish Trap teams need to take out the slowest Pokemon so they can win. I will go on a limb and say have a Helping Hand user that can threaten both Scrafty and Mega Gengar like Sylveon so Scrafty is "forced" to Fake Out this Pokemon. I say this since Helping Hand always goes first before Fake Out so that partner Pokemon can get off a powerful HH attack on either Scrafty or Mega Gengar.
2) Ghost, U-Turn, and Taunters: Basically Aegislash, Sableye, and Gengar (heck even another Mega Gengar) can't be trapped and can switch around when you need them. Just note that Ghost types are likely going to be targeted first so protect them at at all cost. U-Turn and Volt Switch is a great utility move to have so you can escape from Perish Trap, though try to hit yourself to get out of the lock in case you know that a double Protect is coming. Prankster Taunters like Thundurus, Whimsicott, Sableye are likely to be targeted first so pair that Pokemon with something that hurts Mega Gengar or Gothitelle for super effective damage. Remember Taunt can only help temporarily shut down Mega Gengar so it can just easily respond with Sludge Bomb or Shadow Ball.
3) Aegislash and Dark type: Literally IMO the best combo to deal with Perish Trap is Aegislash and a Dark Type like Hydreigon/ "slow" Tyranitar that's not scarf (because Mega Gengar can easily Disable choiced Pokemon). Aegislash has the ability to kill Mega Gengar, however it needs another offensive Pokemon to do so. Tyranitar has a move called Assurance so if you can, run fast Pokemon, or Aegislash with speed investment (like neutral nature that's not Quiet with some speed investment), so you can effective take out one of Mega Gengar's partners other than Scrafty. Assurance, if combo'd or used last, gets a 120 base power (before STAB) and is essentially a Dark type Close Combat so most Perish Trap teams cannot handle a strong Dark hit. Non Choiced Hydreigon can help beat some of the Perish Trap match ups, just don't repetitively use the same move so Mega Gengar can disable Earth Power or Dark Pulse. Bisharp is a great choice as it forces the Mega Gengar user to not pick Scrafty as a lead, though then can just easily lead with another Fake Out user.
Let me go on a limb and say you can't just have one cookie cutter solution to Perish Trap. I mean Soundproof Pokemon like Exploud, Mr. Mine and other stuff all die to Mega Gengar, Scrafty and friends. Perish Trap can be just as offensive as any other team so if you go for Taunt or maybe some other attack to block Perish Song, they could just go for offense as well. That's why I stress that people need to have Pokemon like that can easily threaten Mega Gengar and Gothitelle like Bisharp, Hydreigon, Tyranitar, Aegislash, Krookodile, Sableye (with Quash Lol), and others who can get quick KOs immediately. Once they are at a 3-4 deficit, its extremely difficult for the Perish Trap team to win.
1) Bring Your Best Hyper Offensive Cores and maybe One Slow Pokemon: Basically just have 2-3 Pokemon that can go against Mega Gengar and can OHKO him immediately. Now be weary that Mega Gengar can Protect and for for Disable just to shut down any of your attacks so go after its partner first so you can get some offensive pressure going. The reason why I stress this point so much is once Perish Trap is reduced to 3 Pokemon, it becomes less effective as the opponent may have to sack or let their Pokemon go down. It might be worth noting that Perish Song lets the slowest Pokemon faint (who ever faints last wins in a 2v2) so have something like an Amoonguss or Ferrothorn as the last Pokemon since Perish Trap teams need to take out the slowest Pokemon so they can win. I will go on a limb and say have a Helping Hand user that can threaten both Scrafty and Mega Gengar like Sylveon so Scrafty is "forced" to Fake Out this Pokemon. I say this since Helping Hand always goes first before Fake Out so that partner Pokemon can get off a powerful HH attack on either Scrafty or Mega Gengar.
2) Ghost, U-Turn, and Taunters: Basically Aegislash, Sableye, and Gengar (heck even another Mega Gengar) can't be trapped and can switch around when you need them. Just note that Ghost types are likely going to be targeted first so protect them at at all cost. U-Turn and Volt Switch is a great utility move to have so you can escape from Perish Trap, though try to hit yourself to get out of the lock in case you know that a double Protect is coming. Prankster Taunters like Thundurus, Whimsicott, Sableye are likely to be targeted first so pair that Pokemon with something that hurts Mega Gengar or Gothitelle for super effective damage. Remember Taunt can only help temporarily shut down Mega Gengar so it can just easily respond with Sludge Bomb or Shadow Ball.
3) Aegislash and Dark type: Literally IMO the best combo to deal with Perish Trap is Aegislash and a Dark Type like Hydreigon/ "slow" Tyranitar that's not scarf (because Mega Gengar can easily Disable choiced Pokemon). Aegislash has the ability to kill Mega Gengar, however it needs another offensive Pokemon to do so. Tyranitar has a move called Assurance so if you can, run fast Pokemon, or Aegislash with speed investment (like neutral nature that's not Quiet with some speed investment), so you can effective take out one of Mega Gengar's partners other than Scrafty. Assurance, if combo'd or used last, gets a 120 base power (before STAB) and is essentially a Dark type Close Combat so most Perish Trap teams cannot handle a strong Dark hit. Non Choiced Hydreigon can help beat some of the Perish Trap match ups, just don't repetitively use the same move so Mega Gengar can disable Earth Power or Dark Pulse. Bisharp is a great choice as it forces the Mega Gengar user to not pick Scrafty as a lead, though then can just easily lead with another Fake Out user.
Let me go on a limb and say you can't just have one cookie cutter solution to Perish Trap. I mean Soundproof Pokemon like Exploud, Mr. Mine and other stuff all die to Mega Gengar, Scrafty and friends. Perish Trap can be just as offensive as any other team so if you go for Taunt or maybe some other attack to block Perish Song, they could just go for offense as well. That's why I stress that people need to have Pokemon like that can easily threaten Mega Gengar and Gothitelle like Bisharp, Hydreigon, Tyranitar, Aegislash, Krookodile, Sableye (with Quash Lol), and others who can get quick KOs immediately. Once they are at a 3-4 deficit, its extremely difficult for the Perish Trap team to win.
