I was looking through a text file I had and found this text. I apparently wrote it in response to someone who thought Burmy was related to Pineco. I am pasting it here for archived hilarity, as it seems I never posted it (that I can remember).
I can personally guarantee these 2 Pokemon aren't related. LOOK AT THEM. Geez.
Both Metapod and Kakuna are classified as "Cocoon" Pokemon. Surely Kakuna is a pre-evolution of Metapod.
They both know String Shot and Harden too :oooo
Aside from that, bugs do NOT get pre-evolutions. They are not mammals. They do not grow. Bugs have stages. Either:
a) Larva (baby) - Pupa (cocoon) - Adult (final)
cf. Caterpie, Weedle, Wurmple,
b) Child - Adult
cf. Paras, Venonat, Ledyba, Spinarak, Pineco, Surskit, Nincada, Anorith
c) One-form
cf. Scyther, Pinsir, Yanma, Shuckle, Heracross, Volbeat, Illumise, Korobooshi (maybe)
The only bug to gain a new evolution was Scyther, and that was NOT a natural thing. It has to be traded with an item, where it is coated with steal. There is no visual, textual, nor logical reason to assume Pineco and Minomutchi are related.
If by some act of Satan these 2 are, I will personally drive to the house of anyone who thinks they were and hand them 10 American dollars.
