I was leveling up a lot of weedles and noticed the candy cost rose from 12 per evolution to 25. Does anyone know how many times you need to evolve a Pokemon before its base cost increases?
I think you must have mistaken weedle for another pokemon. The evolution cost will always stay the same. The only thing that changes overtime (for that specific pokemon) is the power up cost. Which may rise from 1 to 2 candies.