As you all probably know, the Quartet is not complete without their enemies: Fall Out Boy has those hooded people who are trying to destroy Rock and Roll (ahem, Rat A Tat), Twenty One Pilots has Blurryface, Tyler's evil alter ego, My Chemical Romance has Better Living Industries, or BLInd, and Panic! At the Disco has... well, I guess those robbers in the Say Amen (Saturday Night) music video. Point is, they need to protect themselves somehow, right? So, here's how I think they would:
Brendon: Based on the Devil's Key Trilogy (Say Amen, This is Gospel, and Emperor's New Clothes) Brendon can "Morph" into a demon! Pretty scary, but good for keeping foes at bay. He just needs to hold the Devil's Key and say "Welcome to the end of eras."
MCR: Mikey, Gerard, Ray, and Frank, by saying their respective parts in the "Future is Bulletproof" speech, can transform into Kobra Kid, Party Poison, Jet Star, and Fun Ghoul, respectively.
Patrick: Even though he probably wouldn't like using it, I think Patrick's ability would be to turn into HIS demon form--you know, the one that killed Joe, Pete, and Andy? The creepy yellow eyed monster? Yeah, you get the idea.
Pete: Since he had one in the YBC, why not here? Pete's ability would be to summon a falcon.
Tyler: Similiar to Pete, Tyler can summon a vulture by saying "Feed me to the vultures, I am a vulture who feeds on prey." Also, he fights with a ukulele, brandishing it like a hammer or sword.
Josh: Josh fights with his instrument, too--he throws his drumsticks.
Okay, this all sounds really ridiculous, but I hope you liked it somewhat :D If you have ideas for how Joe, Andy, Ryan, or Dallon could fight, go ahead and post them!