Potential Max CP of Wild Pokémon

I noticed that somebody had a Pidgeot with a far higher CP than mine, which was maxed out for my level. Initially I thought that was just because I was a lower level trainer at the time - I was around 8 and he was about 20. But later on I thought that the difference (500cp versus 1200cp) was too big to be made just by leveling the trainer.

I began to think that maybe the CP of the Pokémon when they are caught makes a difference. Previously I had assumed that they would just need less.powering up to take them to max if they had a higher CP, but does a Pokémon's starting CP affect their max CP cap later on?

For clarity, if I found a 10 CP Pidgy and a 100 CP Pidgy, will one of them have a lower max CP cap or could I raise them both to the same level in time?

Solution 1:

Actually the difference in the CP is not too big for it just to be trainer level and is quite normal. A pokemon's starting CP will never affect their max CP cap because the cap moves with trainer level.

However a 10 CP pidgy with a higher IV than 100 CP pidgy will have a higher max CP cap simply because it has better base stats.

Link for IV calculator is here.

Solution 2:

The CP when getting a Pokémon don't have anything to do with the max CP it can reach. The individual values (IV) are setting the limits.

You can use this spreadsheet (or this) to narrow down the IV, which are responsible for the max CP.
(You might need a few tries to get the copy it asks you to make, since a lot of people are using it. In the meantime just read the description. It helps a lot.)