Imo the "Dexholder" abilities are what separates them from any other characters. And also, it kinda was continued for later Dexholders (sorta). Ruby was contests, Sapphire was badges, Emerald was symbols, Diamond was emotion, Pearl was willpower, and Platinum was knowledge. Though they weren't referred to as Dexholder abilities specifically, that's probably what Kusaka had for them. Though the Gen III abilities make a bit of sense (though not as much as the previous ones), the Gen IV ones are kinda ridiculous. Emotion, knowledge and willpower are traits for one set of legendaries in one generation, not universal (in Pokemon) traits like battling and evolving. The Dexholder abilities may have been major to the plot earlier on but later I think they were ditched.
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