I'm going to start this off, will be playing Batman :3

It was evening over Gotham, Batman would soon be coming out and keeping the city safe from the evil that lurks within, along with the rogues gallery that waged war against Batman and his crusade. Batman was currently in the Batcave, watching criminal activity on his computer

Batman: Interesting activity here, better keep watch closer, might be clues to the Joker's next plan or something else, or maybe Penguin with his gang or something....

Meanwhile the Joker plans his next scheme with a smile on his face. He laughs loudly.

Batman looked closer at the evidence he had gathered, it looked like the Joker was planning a massive plot against Gotham city, as shown by his activity nowadays. He had escaped from Arkham once again and was planning his attack in the shadows, and it looked like it was going to be chaos....

Batman: I better keep watch, Joker is causing trouble again, and it seems rather disastrous....

The Joker leaves playing cards scattered around the streets of Gotham.

Batman noticed this and observed them, it seemed like a calling card of some sorts, like he was trying to invite him to some location so that he could fight him face to face. Batman remained cautious though, and observed them more clearly....

The cards have pictures of Joker, Penguin, Riddler, and Harley.

Batman noticed this and came to the conclusion that they were in on the plot as well, this was going to be a tough one to deal with since they have all teamed up, but hopefully things could prevail in the end....

Batman: He has allies with him, I better begin calling the others for backup....

The villains watch what Batman's up to by using a secret video camera that was hidden on the cards.

Batman was unaware of this, and begun his plan to interfere in the Joker's scheme to stop him from terrorizing the city and causing mass trouble and chaos everywhere. Soon, he would leave, locate the base and infiltrate the place in order to bring the plot to a sudden stop....

Joker: Thanks to those cards of mine I'll know where the Batman is always.
The Penguin: I made those cards you bragging clown.
Joker: Penguin you may be the smartest one here, but I'm the mastermind.
The Riddler: I'm the real mastermind. It was my idea to use the cards as riddles for Batman.

Batman set out in the Batmobile, in pursuit of the warehouse, he had made sure to prepare himself before heading out, and he had called in Nightwing for backup, who was heading there his own way. It was not going to be an easy fight, but Batman was confident that they would not succeed in the end....

The Riddler: According to the tracking device on the cards Batman is heading towards our hideout.
Harley Quinn: At least we'll finally have company.
The Penguin: Shut up Harley.
The Joker: We'll stop Batman.
The villains laugh as they plan on how to stop Batman when he arrives.

Batman contacted Alfred as he was heading to the warehouse, he had Nightwing as backup but he needed to keep himself informed as this was a potentially dangerous mission.

Batman: Alfred, I am nearing the warehouse, make sure to scan the entrances and look for hostiles outside, I need the nearest way to get in...
Alfred: I'm on it, Sir. All the entrances seem to be heavily guarded, but there is a sewer nearby that connects to the basement, I'll send you the coordinates...
Batman: Thanks Alfred, Batman out...

The villains realize that Batman is getting closer.
The Joker: When Batman comes in here the Penguin will attack him with the umbrella and Harley will use her hammer.

Batman was now near the warehouse, he decided to stop the Batmobile outside the back near the gates and went in using stealth, he made sure to keep watch of his surroundings, and eventually found the sewer, it was located just nearby. Batman went in through there and started making his way to the base...

The villains know Batman's location due to the tracking device. Penguin and Harley are ready to use their weapons to beat up Batman when he shows up.

Batman went through the sewer slowly, he was keeping track of his surroundings and made sure to get there in time. He was sure he heard voices, but he considered them as noise from the engines, when it could be something more dangerous....

Batman: I'm in the sewers, Alfred. Heading to the main base now, although it wont be easy....
Alfred: Good job, Master Bruce. If you keep going in the direction, you can find a ladder to the complex, although I must warn you I am picking up multiple hostile readings...
Batman: I'll take care of them, thanks Alfred, Batman out...

The Riddler: Batman will arrive quite soon. I have lots of riddles for him to solve.
The Joker: Stop giving Batman clues you fool!
The Penguin: Anyways I'll knock Batman out with my umbrella.
Harley Quinn: Well my hammer is going to do more damage to him.

Batman eventually found his way to the ladder, and used his scanner to see that there was about 3-5 goons above, guarding the place. Batman used his smoke bombs, threw them up and eventually made short work of them, it was now time to face the enemies

The Penguin starts using his umbrella. The Penguin: You're going to face my ultimate wrath Batman. My umbrella is loaded with weapons that can knock you out.

Batman arrived into the main room, and he was now greeted by all of his enemies, each armed with weapons. It was time for the main battle to begin, although Batman had thought of a backup plan in case he was overwhelmed, he would keep it in mind, and fight them until reinforcements arrived....

Batman: It's time for all the madness to stop, surrender yourselves now!

The Joker: I have a delightfully sneaky reputation of never surrendering. However your reputation of always defeating me is going to end. Ha, ha, ha, ha!
The Penguin: You don't have any sidekicks to help you this time Batman so you're doomed.
Harley Quinn: Batman's going to be the failing knight this time.
The Riddler: Riddle me this Batman: Who's going to become the knight of failures?
The Joker and the others made cheap jokes while getting their weapons ready.

Batman: I guess all of you and enough to handle me, but we shall see about who walks out the winner...

Batman then launches a bunch of batarangs and then drops a smoke bomb, stunning the enemies. He then grapples up to the ceiling and waits for the next moment to strike against them

The Joker: That darn Batman is so sneaky.
The Penguin: No need to worry my fellow weirdo. We'll defeat Batman.
The Joker: Where is he?
Harley Quinn: We're going to find him.
The Joker, Harley Quinn, and Penguin look for Batman for several minutes. The Riddler realizes that Batman's around the ceiling.

Batman then realises that he has been spotted and comes down really fast, delivering a sharp kick to the Joker, knocking him down in the process. He then made quick work of disarming Harley's weapons and taking her down, but Penguin and Riddler suddenly double teamed him from behind, giving him a blow to the head and taking him down, but Batman was not done yet.....

Penguin: You should give up Batman.
Riddler: Hey. If he gave up this game would become boring.
Penguin: Lets punch him together. That'll hurt him.
Riddler: Okay.
Penguin and Riddler are about to punch Batman.

Batman senses they are about to attack and quickly deflects their punches, and bring's them down with his own punches. He then throws a Batarang at the Joker's goons, disarming their weapons and taking them out of the picture. He was about to do something else, when Joker appeared out of nowhere and took him down with one of his toys, a jack-in-the-box modified to have a boxing glove come out...

The Joker: Give up Batman before I punch you.
The Joker gets his fists ready while the others laugh.

Batman: I'm not surrendering, and besides....you all forgot about the others.....

Suddenly, there is a loud explosion and the roof crashes down to the ground. After the smoke is cleared, two figures can be seen, which are revealed to be Robin and Nightwing, each armed and ready to fight against the enemies

Penguin: Oh no. Two more good guys.
Harley: We may need help.

Nightwing: You're not getting help anytime soon, that has all been taken out
Robin: Indeed, it's now time to face all of us in combat!

Nightwing and Robin then begin fighting Penguin and Harley, making short work of them in the process, despite both of them bringing out all the tricks up their sleeves...