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Sonic Boom. A sonic boom is such a good concept for a move with a couple of ways that it could be used, and what was it? Dragon Rage from wish.com that wasn't even fully accurate.
I feel like the drop of started in gen 2, but wasn't really noticeable because it and gen 3 did still have brilliant psychics, just for reasons other than being psychic.
Not including Miraidon because it's not really the same, Iron Valiant is the only well designed future paradox and the others should have been more like it rather than "What if X, but made of metal?"