NO, the level cap is NOT 100. On Generation 1 RBY, there are glitches where you can catch Lvl 156 Snorlaxes. And battle them. Then they go down to Level 100. Mostly. :)
Also, G1 is by far the best.. other than Emerald and a few others, it's the one where it is EASIEST to catch #151 (Mew).
:)