Pokémon GO’s leveling system sort of sucks. You’re encouraged to pump up Pokémon with expensive stardust infusions, but you will quickly learn that you can easily find another Pokémon at a higher level, and you’ve essentially wasted your resources. For example, I pumped up a 60 CP Drowzee from the start to 120, but later found a 140 one, so everything I invested was pointless. Usually, it seems like the smart play to keep your highest level base Pokémon and transfer the others. Either wait until you have the candy to evolve them, or until you find their evolved form in the wild, then once they reach their second or third stage, really begin to invest. For single-stage Pokemon, it’s hard to tell. I tried to pump up what I thought was a decent 250 Jynx, and lo and behold after spending a ton of stardust, I found a 380 one a few hours later. This aspect of the game can be really frustrating.