Jacket Slogan: Live fast. Die clown.
Harley Quinn: I love the rain, it's like angels are splooging all over us.
Bloodsport: I'm gonna get you out of here alive.
Ratcatcher II: I'm gonna get YOU out of here alive.
Thinker: This is suicide.
Rick Flag: Well, that's kind of our thing.
Bloodsport: We're going to die.
Polka-Dot Man: I hope so.
Bloodsport: Oh, for fuck's sake.
Savant: So, this is the famous Suicide Squad.
Peacemaker: Nothing like a good bloodbath to start the day.
Bloodsport: Noone likes a show-off.
Rick Flag: Here's the deal: we fail the mission, you die.
Bloodsport: We find out any information you've given us is false, you die.
Harley Quinn: We find out you have personalized license plates, you die.
Thinker: What?
Rick Flag: Harley, no.
Harley Quinn: If you cough without covering your mouth.
Rick Flag: Harley! Although that isn't an open invitation for you to cough without covering your mouth.
Starro: Supervillains. Sad souls in costumes, wanting you to think them all dark and deep. What's it like, living life as a punchline? But all it would take would be one blessed act of rebellion for you to restore your dignity in its entirety.
Answer: It's a combination of various reasons. Will Smith wasn't available to reprise his Deadshot role, so there was a shift in the story. King Shark was intended to be in the first film, but the CGI was too extensive, so they went with Killer Croc. In this film, they took the opportunity to bring in King Shark as the "monster" character. But, this film isn't really a sequel or reboot. Basically, this is a new storyline with new characters, and many of the previous characters are just not in the film, with no exposition on what happened to them, and they may not even be part of this film's "universe." The fact that some of the actors play the same character in both films only serves to muddle the concept of this film not really being a part of the previous film's continuity.
Bishop73