It assumed you'd seen BvS? I didn't catch that, and so didn't lose out on anything from that.
I think so. It mentioned a few times things like "what if we're not so lucky next time?" which was a reference to Superman being super powerful, but benevolent. I figured that the general idea of BvS (AFAIK) is that Batman thinks Superman is too powerful and therefore must be stopped because no one should have that much power. And the general idea of Suicide Squad is "we need to stop people/things who are too powerful." So I guess I just assumed it was a reference to BvS because I haven't seen it and don't know what happens in it.
I thought that was a reference to Man of Steel, not BvS. Especially since the other aliens that were there were just as powerful- but Superman was the one that survived. Never put together that they could be referring to BvS.
As for the characters, the following is all my opinion, so of course very subjective:
It might be because you haven't read the comics? Admittedly, with a cast that was this large, it was inevitable that some people would get the short end of the stick... I knew slipknot's position because of this. And I do think that your complaint has merit beyond what you say- it's bad writing. More than the BvS link, I thought this was the point where they relied on you already knowing the characters, though I'm not sure offhand of a better way to execute it in the time given. They are doing a better job with Justice League, but I still give the credit to Marvel, as they were willing to give the major characters in the Avengers their own movies (for the most part), and not rush the project to market as DC is. I'll go down your list interjecting what makes each special- at least the ones I know. I also linked the names up to the wikipedia entries.
Captain Boomerang sounds like one of the silliest supervillains ever. The movie gave no reason or information whatsoever why he was so evil and threatening as to be locked up with the likes of Harley Quinn or Deadshot. It also gave no indication of his "special abilities" that would make him an ideal person for the squad. He's a criminal who can throw a boomerang. Big whoop! That's even more lame than Hawkeye (who I think is pretty lame).
There have been a few different incarnations. The first had no particular background that would seem to make him villain worthy- other than the fact that he made his boomerangs, and they had varied effects, paired with the unusual nature of the weapon, made him a threat for Flash. In Arrow (the TV show) they added the angle that he was Australian Special Forces, and an assassin. So it was his skills with an unusual modified weapon and the ability to get creative with the effects that makes him dangerous.
Slipknot maybe had potential, but obviously went completely unused, so we'll never know.
Nah... he was used the same way in the comics.
Killer Croc reminded me of some mashup of something from Spiderman and The Thing from Fantastic Four and the movie gave me no reason to care about him.
The comparison you're probably drawing is between The Lizard (1963) and Killer Croc (1983), and the parallels are valid, but given more flesh in the comics, as the backgrounds are totally different.
Harley Quinn was the only one of the group (not counting Joker as part of the group) who I knew of before the movie began and I didn't understand her role or her "abilities" in the film. Just because she's crazy doesn't mean she would survive combat (or "perform" it) any better than anyone else.
Her ability is in all honesty chaos, similar to Joker. Her inclusion is more a matter of her popularity in the comic medium, and her popularity there is driven by the fact that she is a relatable female character.
Katana was an unknown who was good with, you guessed it, a katana. But Deadshot could have easily shot her dead before she got to him, so what's the point of her?
You underestimate her, and the Katana. She has great mystical powers from being tied to the Katana and all that have ever been killed by the sword. When Flagg said she could take all of them out easily, he wasn't kidding.
Katana is a highly proficient hand-to-hand combatant and swordswoman, having studied martial arts as a child and later being trained by the samurai Tadashi. From her time with the Outsiders and Batman, she has also developed strong tactical skills.
Katana's Soultaker sword, along with its non-powered twin, was forged in the 14th century by Muramasa, whose swords were said to be cursed and make those who were evil commit evil acts. It sometimes takes the souls of those it kills, storing them inside the sword, where they can engage in limited communication with whoever wields it. These souls can be reincarnated by the means of a sacred ritual, under which they serve their summoner, even if it is against their will. In The New 52, the Soultaker is established as being the 'Sword Totem' of the Outsiders, meaning like the other totems it supposedly bestows immortality and enlightenment upon its wielder, although some like Green Arrow are skeptical of the literal truths of these claims.
Her powers are kept deliberately vague, pretty much so they can cast them to what they need them to be by the souls that are in the blade.
Diablo was somewhat interesting but his character and backstory wasn't developed/revealed enough until too close to the end of the movie. Ultimately I didn't really care about him or his story outside of the small part it played in the film.
He's quite similar to the Ghost Rider in form- another one of those where DC and Marvel cross. He's cursed to be the host for a minor demon, and has pyrokinesis because of that.
Deadshot was the only one who, by the time the movie ended, I felt I'd like to know more about and see a movie about. That said, I kind of feel the novelty would wear off pretty quickly if they tried a full-length film all about him.
Deadshot, other than Bronze Tiger (they didn't show him for some reason), and of course Deathstroke (who they will have in the next Batman film). They have had many different incarnations of him since the 40s, but the one characteristic that has defined him (that they took out) was that he has a deathwish and was a tragic character.
Floyd's parents were the most powerful people in his town, however, they were known to despise each other. Eventually Floyd's mother claimed his father had become "too abusive," prompting Floyd to kill him. When Floyd took the shot from his tree house, he missed and killed his brother, Eddie, instead. From that moment on, Floyd swore to never miss another shot again.
Probably his most defining trait is a desire to die in a spectacular fashion, this being his primary motivation for joining the Squad. He feels he has no reason to continue living, and, while he does not want to commit suicide, he simply does not care if he dies. Various reasons have been cited for this, but the most common thread in them is his parents' peculiar hatred for one another.
I liked the story in the movie... but it still took something from the character that I grew up liking- the original anti-hero long before Wolverine came on the scene.
The Joker was a joke.
Enchantress was a super powerful being whose actions largely make no sense.
I think her actions made sense, but they just didn't do a good job of conveying them. Sort of like in the comics; they never really knew what to do with her.
June Moon was the host for an ancient god-like being (Loa related, but they didn't go there- she also didn't know this until near the end of her run in the suicide squad; she just thought that the totem had done something to her, and it was the totem that was her power). They can't exist outside of their host, and it is possible for the host to resist them, but the more that the host uses the powers, the less control they have. Waller captured her totem (her heart), and it could be used to destroy her. Even after her brother (who was truly a god) protects her, and gives her access to his powers, she was still subject to her totem, just not as much. But as long as she was under his protection, she ignored that fact, in favor of world conquest. It gets sort of sketchy from there.
Incubus was a super powerful being whose actions largely make no sense, and whose name I only know after having looked it up on IMDB.
Incubus was the entity that was inside of June's brother, and more powerful than she. They did an OK job of explaining this, I thought, if less than they should have.
Flag was OK, I guess, but I couldn't figure out what made him any more special than any of the other military folks.
They needed a handler. He was it. Nothing really special about him.
Waller was OK, I guess, but I couldn't figure out why Deadshot, or anyone else, for that matter, didn't just smash/break/shoot/steal her phone/tablet and then kill her and Flag.
Again, her position was that she did have the killswitch and was the power behind the throne, and that was the reason that they were just after her tablet with her alive, rather than dead. If she wasn't in range of the tablet, their bombs go boom. Not in range also means dead. She's supposed to be very much a ruthless power behind the scenes type of person, that thinks several steps ahead of the opposition.