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Gonna be honest, I hated 3rd Versions after Gen 3. Yellow and Crystal were pretty lite updates, and and Emerald was a sort of deluxe edition which bundled Ruby/Sapphire content in one game. I wouldn't call them definitive necessarily, because the originals were alright standalone games. But Platinum was so much more polished and had so much more exclusive content that I started to dislike DP retroactively. It runs slower, has less Pokemon, less online functionality, no Distortion World, and there are "new" Pokemon like Rotom and Giratina O which were unavailable before. Now I will never play DP again.
BW2 was a decent game that filled the same space as a 3rd Version, but coexisting with the original instead of replacing it. The most optimal way to play Gen 5 is to have both games for all the content.