>>56765253Gen 2 or 3.
Gen 1, Rock was unironically considered good; resisting Normal is the kind of thing you put only on a "good" type; the fact that the type is a joke just speaks to Gamefreak's dubious grasp of balance. Not top tier, but "good".
Possibly as soon as generation 2, definitely by generation 3, they were aware the type sucks. Generation 3 had notable rock-ish pokemon just not be rock, put Rock as the first gym to make it easy, not a challenging first boss, and showed at least some awareness of the types shortcomings.
And then in gen 4 they fucked up and gave the bad type a good move, Stealth Rock, not really grasping that the problem with Rock is it's defensive profile, stat trends, and godawful moves, but its offensive profile is a contender for best type in the game
