So I'm just about to finish re-playing Platinum, and with it, I'll have played all four regions recently enough to have this information fresh in my mind.
In any video game, I think it's interesting to note the degree to which you must go through it in a set order. In every game I can think of, you can't just rush to the final boss first--if you try, there's either a physical impasse or some NPC telling you to turn back (although I think it was FFIII where you could try and take on the final boss early, but without completing another quest, there was no possible way to win). The Pokemon games do this a lot--there's quite often trees/rocks/boulders that stand in your way and force you to stop and get gym badges, but the thing I've noted is that the DEGREE to which they do this vastly changed over the generations, with Kanto allowing quite amazing freedom whereas Sinnoh (at least Platinum--don't remember DP) requiring you to beat each gym in an EXACT order.
To list it explicity, each game requires you to complete the following gyms in the following orders:
Kanto (RGBYFrLg)
1. Petwer (annoying guy keeps insisting you challenge Brock)
2. Cerulean (need Cut to proceed)
3. Believe it or not, you can complete the following in any order: Vermillion, Celadon, Fuchsia
4a. You need Surf from Fuchsia to get to Cinnabar
8. Viridian -- Giovanni only comes back after you've beaten the other 7 and, I *think* beaten Team Rocket.
Johto (GSCHgSs)
1. Violet
2. Azalea
3. Goldenrod
4. Ecruteak (need Surf to continue, IIRC)
5. You can get the Cianwood, Olivine and Mahogany gym badges in any order
8. Blackthorn--an NPC will block your way until you get the previous three
As for the Kanto badges, you can get the first seven in literally any order, but you can only challenge Blue last.
Hoenn (RSE)
1. Rustboro
2. You can actually skip the Dewford badge if you don't mind walking in the dark and get to Mauville first, but Rock Smash blocks your way past Mauville, so you need that one before going further
3a. Lavaridge. Again, you can get this one BEFORE Dewford
5. Petalburg. Dad requires four badges to battle him. Beyond that and you need Surf.
6. Fortree. A Kecleon blocks your way
7. Mosdeep
8. You need Dive to go to Sootopolis
Sinnoh (of Platinum. IIRC, there's some minor differences with DP)
1. Oreburgh. Need Rock Smash to proceed.
2. Eterna. Need Cut to proceed.
3. Hearthome. NPCs block the exits until she's down.
4. Veilstone. You can get to Pastoria early, but Maylene is apparently challenging Crasher until you beat her.
5. Pastoria. Need Surf to proceed.
6. Canalave. Need Stength to proceed.
7. Snowpoint. Need Rock Climb to beat Team Galactic, but only thing that's keeping you from Sunnyshore is another obnoxious NPC.
8. Sunnyshore
DPP by FAR has the most rigid plot, but it's also one of the better plot lines, IMO. So Linear Storytelling isn't a bad thing per se... I just thought it was fascinating to see the difference between the original games and the most recent new releases.
In any video game, I think it's interesting to note the degree to which you must go through it in a set order. In every game I can think of, you can't just rush to the final boss first--if you try, there's either a physical impasse or some NPC telling you to turn back (although I think it was FFIII where you could try and take on the final boss early, but without completing another quest, there was no possible way to win). The Pokemon games do this a lot--there's quite often trees/rocks/boulders that stand in your way and force you to stop and get gym badges, but the thing I've noted is that the DEGREE to which they do this vastly changed over the generations, with Kanto allowing quite amazing freedom whereas Sinnoh (at least Platinum--don't remember DP) requiring you to beat each gym in an EXACT order.
To list it explicity, each game requires you to complete the following gyms in the following orders:
Kanto (RGBYFrLg)
1. Petwer (annoying guy keeps insisting you challenge Brock)
2. Cerulean (need Cut to proceed)
3. Believe it or not, you can complete the following in any order: Vermillion, Celadon, Fuchsia
4a. You need Surf from Fuchsia to get to Cinnabar
8. Viridian -- Giovanni only comes back after you've beaten the other 7 and, I *think* beaten Team Rocket.
Johto (GSCHgSs)
1. Violet
2. Azalea
3. Goldenrod
4. Ecruteak (need Surf to continue, IIRC)
5. You can get the Cianwood, Olivine and Mahogany gym badges in any order
8. Blackthorn--an NPC will block your way until you get the previous three
As for the Kanto badges, you can get the first seven in literally any order, but you can only challenge Blue last.
Hoenn (RSE)
1. Rustboro
2. You can actually skip the Dewford badge if you don't mind walking in the dark and get to Mauville first, but Rock Smash blocks your way past Mauville, so you need that one before going further
3a. Lavaridge. Again, you can get this one BEFORE Dewford
5. Petalburg. Dad requires four badges to battle him. Beyond that and you need Surf.
6. Fortree. A Kecleon blocks your way
7. Mosdeep
8. You need Dive to go to Sootopolis
Sinnoh (of Platinum. IIRC, there's some minor differences with DP)
1. Oreburgh. Need Rock Smash to proceed.
2. Eterna. Need Cut to proceed.
3. Hearthome. NPCs block the exits until she's down.
4. Veilstone. You can get to Pastoria early, but Maylene is apparently challenging Crasher until you beat her.
5. Pastoria. Need Surf to proceed.
6. Canalave. Need Stength to proceed.
7. Snowpoint. Need Rock Climb to beat Team Galactic, but only thing that's keeping you from Sunnyshore is another obnoxious NPC.
8. Sunnyshore
DPP by FAR has the most rigid plot, but it's also one of the better plot lines, IMO. So Linear Storytelling isn't a bad thing per se... I just thought it was fascinating to see the difference between the original games and the most recent new releases.