>>58781260I wouldn't call Crystal definitive. Eusine hardly represents Johto to me, Ho-Oh and Lugia are more representative than Crystal, and Johto didn't need a Legendary subplot as its "story". I don't think anyone goes "Wow Kris, finally everything is different", it's such a superfluous addition, and it should show by everyone associating Gold/Ethan with the rival Silver and battling Red. Sometimes it's Lyra, but even then the context of fan art for that is usually vaguely romantic. And Kris rarely got any official acknowledgement after the early DP years.
I don't think Emerald and Platinum added that much to their Gens. Platinum added Articuno, Zapdos, Moltres (available in HGSS), Regirock, Regice, and Registeel (only available through Pal Park otherwise, but requires a fateful encounter Regigigas to even find them), Tangela/Tangrowth (Ranch/HGSS/Pokéwalker) and Tropius (Pokéwalker) to Gen IV. And this is at the cost of Murkrow/Honchkrow (Diamond/HGSS/Pokéwalker), Stunky/Skuntank (Diamond), Misdreavus/Mismagius (Pearl/HGSS/Pokéwalker), Glameow/Purugly (Pearl), Trapinch/Vibrava/Flygon (DP/HGSS/Ranch in Japan), and Clamperl/Huntail/Gorebyss (DP/HGSS). You could say that Platinum made a number of dual-slot mode lines part of the regular Pokédex and not tied to GBA cartridges (Magby/Magmar/Magmortar, Elekid/Electabuzz/Electivire, Gligar/Gliscor), but even that's kind of reaching. Platinum is still the overall better game, but I think its additions weren't that big in the grand scheme of what DP already offered and what was unique to Gen IV. Emerald gave Hoenn the post-game it desperately needed, but once again, many of its additional 40-ish Pokémon could already be obtained through other methods by that point, only Mew was ever truly exclusive to Emerald.