Any sources online will only tell you about the general rules and numbers for the cartridge games, this isn't always the case for PRO although it is very similar..
One thing I will tell you though, that the stat caps for evolved pokemon are much higher, and if you wait until literally the last couple levels (ie, 98/99) you will end up with a weaker pokemon out of laziness than if you evolved at maybe 80-85 because they won't have time to catch up with the stat caps. I have heard people talk about this and go 'oh, yeah, but they will level faster'. Sure they will, but if you really want strong pokemon, spend the extra time to level a fully evolved pokemon a good 20 levels or so so it can catch up with its stat cap :)