>>20869915>>20869934It had a niche, which is more than can be said about Charizard (which was weak to Blizzard in Gen 1, about as bad as being weak to Psychic) and Blastoise (a non-Slowbro/Starmie bulky Water without recovery, eh?).
Venusaur had a fast reliable Sleep Powder, beating out Exeggutor's pissy speed, and had the only good Grass STAB in the game with Razor Leaf, able to OHKO the Rock/Grounds and do significant damage to Starmie. It thankfully had Sword Dance and could basically blast off boosted Body Slams for the high Special mons (who feared the Paralysis) and always critical Razor Leaf on those that were weak.
That's about where its good points drop. A +2 Body Slam 2HKOs Alakazam, who 2HKOs with Psychic but outspeeds. You can either risk the parahax to win, but most often it was forced out. Starmie had a chance to 2HKO if it avoided the low damage rolls (good for Venu since non-guaranteed 2HKO), while Venusaur got a solid 2HKO at ~80% per RLeaf but was outsped. It also did jack against Gengar (who in turn does jack to you aside put you to Sleep).
The biggest condemning factor was that at +2 (and you're never getting more than one free turn in Gen 1 OU), it failed to 2HKO Chansey, meaning its mixed offense was effectively a moot point. Otherwise it'd have been one of the few effective mixed attackers in the tier not named Tauros.
As it is, it'll only ever be the second best Grass in the Gen 1 environment (and Exeggutor is the best Pokemon in the Gen 1 meta period, with access to Sleep, Explode, Psychic, Stun Spore, and even Mega Drain).