There have been several reports of the sidings in Civil War including these:
Pretty much every Avengers character that DOESN'T have their own franchise is going to appear in CIVIL WAR. Some we already know about, including Cap (obviously), Winter Soldier, Falcon, Black Panther, Black Widow, Iron Man, and Hawkeye. We can also confirm the recently rumored Scarlet Witch, as well as The Vision, War Machine, and even Ant-Man. The non-hero villains are, as already confirmed, Baron Zemo and Crossbones.
In terms of who's facing off with who: So far it looks like Cap, Black Widow, Hawkeye, and Falcon vs. Iron Man, War Machine, The Vision, and Ant-Man, with the Scarlet Witch and Black Panther somewhere in the mix
As for Spider-Man; Marvel is playing it close to the chest, so there's no info on how he's involved...yet
We all know that Chadwick Boseman will appear in CIVIL WAR, but his role in the war isn't one-sided as he'll have his own agenda in the film. There's been speculation that he'd take the Spider-Man role as it plays out in the comics, but that doesn't look to be the case. Either way, his involvement will still be significant
Plus Falcon Will be getting an upgrade
The Falcon will, in fact, be getting a costume upgrade for CIVIL WAR, which will be a modified version of his WINTER SOLDIER suit, but with grey and red colors, as per his comic origins. Captain America will be carrying over a slightly modified version of his AGE OF ULTRON suit, and so far The Winter Soldier will look very much as he did before, long hair and all. The coolest costume news is for Crossbones. Many of us are dying to see ol' Brock Rumlow in his trademark get-up and that will indeed happen. He's described as "messier" and the skull imagery on the suit is described as "graffiti-esque." And yes, he does indeed wear the skull mask that covers his entire face, which is said to be a hybrid mask/helmet. Think Army of Two
In Mark Millar's Civil War story the catalyst that sets off the "Civil War" is when the New Warriors destroy several city blocks in an attempt to apprehend a supervillain, causing the deaths of more than 600 civilians, prompting the Superhero Registration Act, which requires all superpowered beings to register with the government, reveal their secret identities, and receive "proper" training and operate under the employ of S.H.I.E.L.D. Obviously, this has to be changed for the MCU version, and this is the basic premise; Instead of the New Warriors being the catalyst for the Superhero Registration Act, it will be Crossbones (in costume) who will be the catalyst that kicks off the film, instigating an attack that causes much death and destruction, causing the government to step in and put out the Superhero Registration Act.
The other element that will be a key focus is The Winter Soldier, whose existence is the big question as he has the ability to be a hero, but has also been a villain. This causes the main rift between Tony Stark and Steve Rogers, as the disagreement leads them to opposing sides
Now back to the article....
Let's get to it:
Iron Man's "Team"
Obviously, if War Machine will make it out, he will be on Tony Stark's side.
Not only for the reasons that he is Tony's best friend, and he got his armor from him, but he is a military man at heart.
He would totally support the Registration
Hawkeye would support this because he is more loyal to SHIELD, and knows he shouldn't test his luck since he already was a fugitive in Avengers.
The Maximoff Twins
Everyone is saying "Quicksilver will die!" I reply NO!
Again, The Maximoff Twins are siding with Stark not because it is right, but because they need the "protection"
Once again, a military person.
An Air Force pilot, Captain Marvel would be totally join the side for the registration.
Possibly, though, she could appear Pre-Marvelization
Black Panther was originally supposed to have Spider-Man's role, but with the announcement, we are led to believe he will have a different role.
At least in Avengers EMH! (Never should never have been canceled), the new Black Panther, after T'Chaka (his dad), looked to restore diplomatic relations between Wakanda and other nations, so it makes sense that he would side with the government.
Tony Stark could program the Vision to do it.
Even if it is of his own free will, Vision will side with the government because it is the "logical" thing to do.
Either way, Vision is awesome
Again, these guys are definitely on the wrong side of the law.
They probably won't appear, but it would be SICK if they were
Thor won't actually be in the film
It will be: RAGNAROK!
The clone from the original Civil War storyline (AWESOME), the real Thor was dead. He won't be dead, but he will probably be back in Asgard
The scene in the trailers could be when the Avengers blame Tony for making Ultron, and then he showed them the schematics, they asked to see all of them.
Then Thor sees the schematics for both the Thorbuster armor and Ragnarok
Ant-Man will side with Cap because he has nothing to lose. "The Ant"'s identity is already known because Hank got him out of prison, so the authorities must know why.
He knows what is right, and will fight for it to look good in his daughter's eyes (Is Young Avengers possible in el futurablo?)
Falcon will obviously be on Cap's side.
No explanation needed
Black Widow will be on Cap's side because her identity will need to be kept
If anyone knew her past, she would be murdered or arrested
I know, not the best reasons, but I was watching Psych while writing this, so my mind was blurred.
Previously said in the rumors, Winter Soldier will be one of the catalysts of the Civil War.
He will need Cap to find out what he needs to know. I feel like he is halfway through recovering from brainwashing. He will need some answers, but he will know he can trust Steve no matter what.
Doctor Strange is one of the heroes who has a still-secret identity.
He could be still stuck in vigilantism, and needs to protect his identity.
Of course, Spidey will have the exact same role as he did in the comics. He will end up on Cap's side after going through the Iron Spider thing.
Hulk will need to side with Cap. DUH!
If anyone knows about the destruction that he caused as the Hulk, he'd have a BIG, green problem (get the pun?)