I'm thinking Weedle/Beedrill could go up. Bug-type moves are super-effective against poisons in this gen, so that's 4x effective against the common grass/poisons and nearly everything in Erika's gym.
It also learns Agility and Swords Dance. When up against Sabrina in Yellow, use Agility once then tear through everything with Twineedle. Far more reliable than most others strats you can think of.
You're also agreeing upon Psychic-type's exceptional value, which I assume has more to do with the poison-type being everywhere than 30% likely special falls or absence of dark/steel types and ghost moves.