Here before I start let me tell you about the different rankings and such
Pokemon potential ranking :
Red - lowest
Orange - low
Yellow - basic
Gray - good
Green - excellent
Blue - elite
Purple - legendary
Pokemon potential ranking is the ranking about what's the growth potential of a Pokemon and how quickly and how far it could grow it's also dependent on the race of Pokemon
Trainer potential
Rank 1 - better if he don't come to Pokemon line
Rank 2 - good enough to take care of Pokemon
Rank 3 - good enough to participate in league and travel around the world
Rank 4 - at this rank you have the potential to become a great trainer
Rank 5 - at this rank you have enter the elite of Pokemon society (gym leaders)
Rank 6 - at this rank you come in the category of the elite 1% of trainer society. (elite 4 ) level talent
Rank 7 - you are at the elite 0.01% of trainer society like the different league champinos
The trainer ranking are given by league