I also decided to take a close examination of the trailer. Most of my comments are trying to figure which location is being shown, though I will make some observations which I'll color red for convenience:
0:26-0:28: Professor Oak's Lab?
0:28: Pallet Town, there's even the "Technology is Amazing!" guy.
0:28-0:29: Route 1 most likely. It has set pieces from it, but it's not exact.
0:29-0:30: I don't recognize the town/city, though if the trainer went through Pallet Town and Route 1 the most logical thought would be Viridian City. Eitherway, I think it's clear that some redesigning of the routes and towns/cities have been done. It's Fuchsia City.
0:32-0:33: Once again, in Oak's Lab meeting the Starter. Combining it with the previous one this "bonding moment" happens first and then it jumps on your shoulder/head as you get ready to head out into the world.
0:34: Pewter City.
0:35: Viridian Forest? If this is the very beginning of it, the bottom right corner, they removed a patch of grass.
0:35-36: Vermillion City.
0:43-0:44: End of Route 1? It's missing the left end where there's a ledge you can jump down to easily get back to Pallet Town without having to go through the grass. Though, now that Wild Battles are visible, I guess there's no need for such a shortcut so they can actually shrink down Route 1. Though I can see some long time fans considering that a bit sacrilegious. False alarm, it's Route 2.
0:47: I wonder what the "Help" option does. Is that how you can get a friend to enter the battle and help with a double Poke Ball throw?
0:51-54: DRAMATIC CAMERA PULL-IN!
1:04-1:09: End of Route 3 and entrance into Mt. Moon.
1:10: Obviously inside Mt. Moon. However something more important happens at this moment: a Pokemon spawns in! Near the ladder you see a Zubat suddenly appear in a puff of smoke. So you don't need to be off screen for spawns to appear, they'll just happen periodically.
1:11: Player 2 doesn't have the "Help" or "Run Away" option. Player 1 still has the "Help" option available even though there's someone playing wih them. Maybe "Help" will let you use the Pokedex to examine the Pokemon your catching?
1:19: Do you really need me to tell you that's Route 24's Nugget Bridge?
1:20: Well they kept the names of the trainers consistent between this and FRLG, first trainer on Nugget Bridge is Bug Catcher Cale.
1:21:
- Hey, wait a minute, Cale never had a sole Venonat! In RBY he had a Caterpie and Weedle, FRLG also giving him a Metapod and Kakuna. NOT MY GEN I!
- Okay, joking aside, hey, past Pikachu315111, before you began spouting out about Pokemon only have two moves or how they may have changed the number of Pokemon in the party you probably should HAVE CHECKED THE TRAILER! Because it clearly shows here that the number of Pokemon in your party didn't change from six and you can have up to four moves. Genius research. But, yeah, so since you can access the PC from your bag and switch out anywhere, as well have a friend co-op in a battle using one of your Pokemon, what's the difficulty of the game?
1:35: Route 17? Aka the Cycling Road? But you can't access this place without a bike and can't get off your bike once on here. Unless, since you can ride Pokemon, did they remove the bike?
1:42-1:43: So, the Pokedex looks to now also count how many of a certain species of Pokemon you caught. Also, it looks like different members can have slightly difference in height and weight, the Pokedex showing you the lowest and highest which you caught.
2:16: Catching a Magmar in the Pokemon Mansion... something which can only be done in Blue version. Hmm, that's something to think about, how will they do version exclusives in these games? Will Pikachu have the Red exclusives and Eevee the Blue (or vice versa)? Will they have a unique list of exclusives? Would be interesting if Pikachu kept the Yellow exclusives while Eevee then got the Pokemon which were left out of Yellow.
2:19: So, exactly what is the requirement for riding a Pokemon? Okay, one is it has to be big enough to carry you, but is there a limited list of such Pokemon, like it has to be on the Pokemon's back? Also, when it comes to flying Pokemon what's the rules? Do you still need to stay on the route but are allowed to fly anywhere? What about landing? Cause in RBY, you get Fly before Surf, so unless they change that this kind of makes Surf pointless aside for Pokemon encounters.
2:20: End of Route 17. How do I know? Outside the Pokemon Mansion, the only place to catch a Ponyta is in Yellow on Route 17. And yeah, looks like they completely changed Cycling Road as there's now a Picnicker standing by the end.
2:21: Underground Path from Route 5-6. Cute idea having the parallel red and blue stripes so players can have races against each other.
2:22: More of the new Route 17? Route 14. Well, something else caught my eye here: two trainers standing next to each other. Double/Tag Battles?
2:27: Catching a Haunter in Pokemon Tower.
2:28: Look like there will be some kind of Pokemon Refresh feature, though will it only be for your Starter or can you do it with all the other Pokemon?
2:29: Pokemon customization, definitely only for your Starter. Cute idea and something I wouldn't mind in the main games. But can you customize your trainer too? Seems rather silly to only customize Pikachu and not give the option to the player, at least giving the same set of clothing so you can match each other.
2:31-2:32: Team Rocket of course and looks like it's in Silph Co..
2:33-2:34: Battling a Fisherman aboard the St. Anne?
2:36: Cloyster using Shell Smash? If so that confirms more than Gen I moves.
2:37: I think that was Seismic Toss being used on a Magikarp.
2:48: More of new Route 17? Though more importantly, blink and you'll miss it but item balls on ground still around.
EDIT: Maybe I should have first looked for a video for also someone pedantic enough to match all the in-game locations: