>>13814330venusaur was pretty meh, and only became decent in Gen 4 and OU in Gen 5. He's really only better now because the metagame changed too much and poor charizard (and blastoise, to a lesser extent) couldn't keep up.
as you said, feraligatr is the best of Gen 2. no arguments
In gen 3, all the starters were good, but swampert and blaziken were top-tier OU threats.
In gen 4, torterra was definitely the worst starter
And in gen 5, serperior suffers from LOL NO MOVES.