I keep asking questions that are hard to answer myself. I think I'd go Wartortle or Gengar.
I suppose my luck with the RNG in battle is coming back as no luck avoiding dupes. Although... I think I might switch my plans up a bit and check out routes 5&6 (I believe you get access after visiting bill) for a bellsprout before taking on Misty.
As a side note, part of my reasoning to hold back Pokey, if the first team fails against Misty, I want at least a minor advantage on my roster for a secondary team instead of none.