White (weakest)
Red
Indigo
Violet
Black
Sliver
Gold (strongest)
The potential above mentioned are the potentials that the Pokemons will have but it doesn't mean that the potential will become a sealing even if a Pokemon has a white potential it can still reach god level through hard work but it will be extremely difficult.
Only use of having higher potential is that pokemon will gain more experience and level up faster than the counterpart who will have less potential. Another advantage they will have is that they will have easier time in understanding a move and gaining a mastery over it.
Common Pokemon that we can find in abundance such as beedrill will have low potential whereas pokemon like Dragonite will have high potential as they are rare pokemon.
Gold level potential will be found in legendary Pokemon and will be rare in it and 1 in a billion in other Pokemon .
Whereas sliver will be found 1 in a million.