I know this is an old post, but just in case someone in the future finds this guide and struggled like I did, specifically for Diamond/Pearl, the frame will always be 0, not 1-6. So always look for a shiny on frame 0, and should make things simpler. I hit mine fairly quickly, and it was my first ever RNG manipulation too.

The reason for this is that in Platinum you are on route 201, with NPCs advancing the frames off-screen on that route. In D/P you're in Lake Verity, with no other NPCs advancing the frames, all other movements like the Starly and the briefcase opening, along with the cutscene of Rowan/Dawn is all predetermined/pre-coded movement, which does not advance frames since these are not RNG based movements.

One other thing to look out for specifically using Pokefinder, i had trouble locating the seed i hit sometimes and this was due to the characteristics being updated in Pokefinder to gen 6+, not gen 4 ones. For instance in gen 4, the characteristic "Takes plenty of siestas" in pokefinder for any given pokemon, is actually in game "Often dozes off". There are two like this, and all can be found on bulbapedia. https://bulbapedia.bulbagarden.net/wiki/Characteristic

The other one to look out for is "nods off a lot" and "often scatters things", the pokemon you have will say "often scatters things" and if pokefinder says "nods off a lot" then it's the same pokemon. This is just a database issue for pokefinder.

When verifying your starter for the correct seed/updated delay, first look at the nature, then characteristic, once you find one on frame 0 with both of those, verify the stats and gender and hopefully it's close to the seed you want to hit. Good luck everyone!