Why is the lower IV one such a good CP?
SneakyGremlins Because CP and IV are in no way related.
Having a high CP doesn’t mean it will have good IVs; it doesn’t even mean it’s more likely to. There’s no link there at all.
CP can be changed, hence its lack of importance. IV cannot be changed, which is why it is so important and the reason I only want 90%+ IV Pokemon, even if they’re an exceptionally low CP.
But as above, you do need to be careful. Powering up a Pokemon below level 20 can have astronomical stardust and candy costs. For example, it takes 66 candy and 75,000 stardust to take a Pokemon from level 20 to 30, and 86 candy and 96,400 dust to take a Pokemon from level 15 to level 30.
However, out of all the Pokemon released in game, only a small few of them are worth powering up; powering up anything else would be a massive waste.