>>35929791people are missing the main reasons eggy fell (and why it was used in the first place)
sleep status is essentially death in gen1, so is getting boomed on. eggy can pretty reliably do both in a game, which is very desirable in a game filled with unkillable fatasses like chansey, snorlax, and eggy itself
by gen 2, sleep was not nearly as bad and most things were sleep talkers anyway
by gen 3, the change to evs meant eggy no longer had max power booms, and the rise of steels+gengar meant boom wasnt even a surefire way to trade anymore (gengar had always been good, but it got a lot better in gen3)
everything eggy accomplished before can be done better today with a smeargle that knows spore and endeavor
i wish todays eggy had an ability to set trick room upon switching in for 3 turns; i feel like its the most iconic user of the move in the games