It's not exactly a " How it's done " kind of thing.
Different pokemon have different maxes, normally a pokemon with a higher base in a stat are the ones that will have higher numbers when trying to max out a stat when EV training, so to be honest. Ev's can easily vary a lot between different pokemon. This is why some pokemon can have like 196 and be maxed out in a stat, when others can have like 180.
When using PO, you just have to keep tweaking the Ev's until it stops rising.