>>29172138Red and Blue were really the only gen with relatively underpowered majority of Legendaries. Mewtwo and Zapdos were the big threats, and even Mew due to its diverse movepool.
As soon as gen 2 came out, there were the three legendary beasts to deal with, not to mention Ho-oh and Lugia who are difficult to take down even today if the set is bulky enough.
From then on, most Legendary Pokemon have been powerhouses in their own respects, whether it be as a staller, tank, glass cannon or straight-up sweeper.