Obviously you'd first have to sell it to Sunrise and, by extension, Bandai. Normally I would've thought this would have been harder but with Sunrise and Level 5 Studios cooperating to make Gundam AGE, I take that as a sign of them being willing to let outsiders come in and work on Gundam. Next would be design. Personally I would go with a production design that would look both futurisitic and kinda retro, the retro as a nod to the fact that Gundam was made all the way back in 1979. I would probably ditch the pink EFF women's uniform. You'd probably get some loons here in the states complaining of sexism or something. Maybe make them red or white? Maybe have everyone where the tan and black regular version?
I wouldn't change the designs of the MS greatly. The mono-eyes on the Zeon mechs would definitely have to be fully red. Would probably look more intimidating that way. I would ditch the ugly-as-frak Zeong that Char got at the end for either a Gelgoog or maybe a full design of that wierd Gundam that Char could have had. Actually I really like this idea! I'd go with it unless some exec raised a big stink about it. Can't mess with the design of the Gundam too much either. I'd probably make it look like this version, but not too different. If nothing else, the Japanese fans would scream bloody murder if the Gundam was 'desecrated.' Besides, when you really think about it, how is it any sillier than a robot that turns into a Camaro or a robot that boxes? The Guntank and the Guncannon... I'd have to leave those to people with more artistic ability than myself! And sorry Neo, but the Guntank would likely get ditched ASAP and be replaced by a second Guncannon or something, like the animated movies. Some of the Gundam's extra gimmicks, like the Gundam Hammer, would probably have to go as well.
Overall, the effect I would go for wouldn't be utter realism but just to make sure that the MS, ships, planes, etc. looked good in live action.
Next, casting. This would likely be one of the most fought over parts of the movie. I know a lot of people didn't like the fact that that Avatar movie had a buncha white Disney kids in it but let me try to make some educated guesses. First off, Amuro. After thinking about it for a while... I think that a Caucasian actor would have to play Amuro. I stare at his picture from the MSG, Zeta and CCA and I just don't see an asian actor. The trick would be finding the right one. One of the things I always laughed at Smallville for was the fact that it was absolutely impossible to pass Tom Welling off as a High School Freshman, so you'd really have to find someone who looked the part. And especially not Zac Efron (isn't his career over anyway?) or Goof LeBeauf. Maybe Elijah Wood?
Bright Noa... there's some confusion on him. Doesn't it mention at one point that he's from Hong Kong? I don't want to spread the Bright-is-british meme, but it's possible. You know what? I'd hire an asian actor just because, when was the last time you saw an asian actor as the captain of a sci-fi warship? Maybe get the guy who played the Korean dude on Lost? And if he had to be a white dude ('cause the studio forced me into it): Nathan Fillion
Mirai and Hyato would be played by asian actors because... they're names are MIRAI YASHIMA and HYATO KOBAYASHI. Doesn't get more Japanese than that! As for Mirai: either Maggie Q, Jamie Chung or Grace Park. Possibly Crystal Liu although I'm not sure if Crystal can actually speak English.
In my perfect little world Sayla would certainly be played by... I... don't know. Seriously, I can't think of a contemporary actress that I would trust with the role. Maybe I'd have to go unknown. Maybe Jessica Alba. Maybe. Katee Sackhoff? Hmmm...
Char... oh dear Char. He'd have to be a white guy. Have to be. I'm sorry, I just can't see a blonde asian guy playing THE Char Aznable. Matt Damon maybe. Or wait! Even better: Chris Pine! Char would have to lose the bucket though. As has been said before, Char's bucket is nowhere near as cool and/or intimidating as Darth Vader's. He'd have to where the mask Full Frontal style, but without the red eyepieces.
Aye Carumba, I don't want to sit here and cast the movie all night. Obviously I'd ave to go with who I felt was best for the job. Hire Chris Pine? Sure, as long as I felt he was right. Go with unknown actors? If I had to, I would, even though it would be a gamble. Can you imagine what Star Wars would be like today if Harrison Ford, Carrie Fisher and Mark Hammil had been crappy actors?
Oh but Scarlett Johansson would be Lt. Matilda. Non-negotiable. And Edward James Olmos would be General Revil, just because I know it would make Chris, Neo and Soul Bro very happy. And after what Alan Tudyk did in TF3, he'd have to go in there somewhere. Maybe as Job John? And Rachel Weisz would be Kycilia Zabi. Okay I'm going to stop now.
Okay, enough of that casting crap! Now on to the real meat and potatoes of this ensemble: the story and how it would be organized. First of all you'd need to have two very clearly defined things: character development and good vs. evil. Now I know that good vs. evil isn't really Gundam's main schtick (even when they were faced with what the Titans had done in Zeta Gundam, it always less about beating the Titans and more about how people's souls were being pulled down by gravity) but what I mean is, you need to make sure that there are clearly defined good guys and bad guys or you're going to lose the audience. And there will be absolutely no Zeon apology or fanboy-ism here, no sir! The first few minutes of the movie will be an introduction about Universal Century and the war. I'd show colonies getting nuked, Zaku II's gassing colonies (like in 08th MS Team) and I'd show the ever-so-famous Operation: British (why is it called that anyway?). There has to be no doubt in the audience's mind that the Zeon are the BAD GUYS. Of course the Federation won't all be saints either but it'll be obvious that they're in the right on this one.
As far as the characters go, you would of course not sacrifice character time for cool robot battles. Quality over quantity. The trick of course would be to balance it out through three movies. I would try to keep things like Amuro meeting up with his mom and the famous Brightslap scene, Sayla meeting up with Char at one point and so on and so forth. Sayla and Amuro would eventually end up together. I like this pair, it's in the novels, I'm sure if we were careful with it, it could work. I'm not even going to begin to speculate if they would make any more movies after this so I'd just let it run it's course. You'd see Bright and Mirai's relationship (and the business with Cameron Bloom) but it would definitely be more in the background.
Okay, so assuming that you could convince some studio somewhere to let you do the whole trilogy, I'm willing to be that you'd probably be able to only get about... 150 minutes tops. If that. So, how to spread the whole story of Gundam into three 2 and 1/2 hour movies? Weren't the compilation movies longer? Anyway, it could be done if you were careful. Like I said, the beginning of the movie would be a short intro about the war and then we'd move straight into the action on Side 7. This would probably take a while because you'd have to establish so much and you would need to have Char and Amuro's first duel. And Char's Zaku II would need to actually be red, not sorta pink/red. I'd probably skip all the stuff that happened on Luna II and just have Char chase the White Base all the way to Earth. Also, Captain Cassius would have died in the Zeon sneak attack, so a large part of this first movie would be Bright and the other junior survivors trying to get these civilians to work with them.
Once on Earth, you'd move into all the drama with Garma and such. I'm thinking that you could end the movie either with the White Base shooting Garma down and then Ghiren's famous Sieg Zeon speech or a duel with Ramba Ral where Ramba would get to say his famous "This is no Zaku boy!" line. The Ramba duel would be a good cliffhanger ending because the uninitiated would hopefully be curious as to wether this new guy is going to beat Amuro or not, but I'm more partial to the Ghiren speech. it would be an ominous note to end the first movie on, as the camera pans over the Zabi family and legions over uniformed Zeon soldiers. Yeah, the White Base might have beat Char and Garma, but there's the rest of Zeon they have to deal with.
Now the second movie. If you went with the Ghiren speech ending for the first one, you'd plunge back into the action with Ramba Ral showing up, Matilda showing up, Newtype nonsense and Amuro losing his marbles. You know, I'm sitting here typing this, doing my darndest to remember how things go in Gundam, so feel free to correct me if I really get something in the timeline wrong. At this point you'd have to have the scene with Amuro's mom and how he is starting to change and also show his Newtype powers evolving. At this point you's also have to show Amuro's and Sayla's relationship evolving and how he's drifting away from any romantic overtures of Fraw.
Now, I'm thinking that the overall plot of movie 2 would have to be the Battle of Odessa. Movie was an escape, with the White Base trying to get to Earth and then having to deal with the combination of Char and Garma. Movie 2 would be about the White Base trying to get to Odessa in time to support the attack. Now IIRC, the White Base wasn't at Odessa in the original series but I don't think you could have the characters miss out on such an important battle in this type of movie. This would be where Amuro would tangle with the Black Tristars and where Matilda would bite the dust. Speaking of Matilda, I would definitely leave in the goofy every-blue-shirt-on-White-Base-takes-a-picture-with-Matilda scene. And speaking of her death, what would you think is more poignant: Her watching as the Dom swings down and crushes the cockpit or closing her eyes right before the final blow? In any case, the movie would end with the Zeon finally on the run with the White Base mourning the death of another comrade. Of course Ryu would have died earlier in the movie.
Movie numero tres! Since there's a whole lot of stuff that needs to go on in this movie, I might just dump the attack on Jaburo, or have in more limited form. Maybe Char infiltrates the base and runs into Sayla and tries to convince her to leave White Base again. In any case the action would finally move to space. You'd probably have to have the scene where Amuro meets Lalah and Char on Side 6 near the beginning as the EFSF fleet gears up for Operation: Star One. You'd also have the drama between Bright, Mirai and Cameron Bloom. What I'm not sure about is the bit with the Texas Colony. Do they learn anything about Newtypes there or was it an excuse for another robot-of-the-week battle with M'quve? Anyway, the Battle of Solomon would be near the midpoint of the movie and signal the final collapse of Zeon. At this point, the movies will have been dropping all sorts of hints about the Zabi siblings' political squabbles, especially between Ghiren and Kycillia. After Solomon you'd see Degwin trying to negotiate peace with Genral Revil and Ghiren's betrayal. The last 30 minutes or so of the movie would be the Battle of A Boa Qu. As I stated earlier, no Char flying a freakin' ugly Zeong around, unless Sunrise holds the proverbial gun to my head. I'd also leave in how Amuro and Char start in their MS, blow the crap out of those, switch to guns and then finally finish with swords. Not forgetting, of course, the famous "Last Shooting" scene. I'm pretty sure the Japanese fans would crucify me if that wasn't done right! Also the White Base would be getting blown to pieces, Kycillia would shoot Ghiren, Char would blow her head off with a rocket launcher, so on, so forth. Even with the White Base and its MS destroyed, most of the crew makes it off alive and there's a joyous reunion with Amuro, the Federation wins the war, the Zabi are all dead, the end. Oh, I almost forgot about the Elmeth! Depending on time constraints you'd either have to do that right before A Boa Qu or during the battle.
Also, you could have a closing montage during part of the end credits, showing the signing of the treaty that ends the war, what post-war 0080 looks like, the characters going their separate ways, etc. Lastly, at the end of the credits, you show these two mechanics talking about how it's a shame that the EFSF didn't get to use the new unit and about how the Federation maybe planning to build more. As they leave the hangar, you pan up to see the RX-78NT1 in its hangar. Really The End.
Promotion would be difficult anyways, so I'm not going to break that down too much, 'cause you know that there'll be neckbeards saying stuff like, "I don't want to watch a robot that looks like a space samurai!" or "This looks like a Japanese Star Wars ripoff!" We'll have to see. I mean, the Transformers movies did tons of business, we've got that Real Steel movie coming out and that new BATTLESHIP movie seems to have some kinda flying alien mech thing in it. We'll see.
Lastly, music. Since I'm American I would be sorely tempted to get someone like John Williams, Hans Zimmer, Howard Shore or Steve Jablonsky to do the soundtrack. But I'd be willing to bet that Sunrise would want me to use Gundam's original composer. Or maybe Kou Otani or somebody. As long as the soundtrack kicks absolute butt, I wouldn't mind.
Okay, I'm done, someone else start talking.