>>41474373Better Pokemon distribution, better performance, introduced Looker, reworked trainer rosters, added the Vs. Recorder and introduced the replay system that we have today, changed level up moves of certain Pokemon to make them more viable, introduced foreign Pokedex entries for foreign Pokemon obtained through trades, this feature has also carried over to modern Pokemon, graphical update to almost every single area.
There's a lot of other features, but it's fair to say that Platinum was actually a pretty thorough overhaul of many different facets of Diamond and Pearl, on top of that it introduced a lot of features that are STILL in modern Pokemon games.
I think this is why we need a third version of Pokemon games, a game that fixes the issues of the base games that launched earlier, adds new story and depth and is overall the "definitive" version of what these games are supposed to be. X and Y needed a Z, Omega Ruby and Alpha Sapphire needed a Delta Emerald. Gen 6 would have been so much better if a third more optimized and fleshed out version of these games were released. Gen 7 kinda did this with USUM, but those changed a lot of the story and didn't really overhaul much. Performance was still dogshit in anything but single battles unless you were using a New 3DS.