Please can you tell me?

So, a good Pokemon team for the game consists of a fire, grass, ground, ice, dark, fighting, and dragon pokemon.

In the beginning, make sure your starter is Chimchar; as an Infernape, he will cover the Fire AND Fighting types.

When you get a chance, catch a Budew; if you prefer to make it easier on yourself, wait until you can catch a Roselia; if you evolve her into Roserade, you'll have yourself and awesome Grass pokemon.

On Route 217, catch a Sneasel! Evolve him into Weavile for an awesome Ice AND Dark Pokemon.

Garchomp is an awesome Dragon AND Ground Pokemon to consider. When you find Gible in the secret entrance to Wayward Cave, be sure to catch him and evolve him at level 48.

Thus, we've covered all the types you need for the game! With 2 Pokemon left in your team, you can consider having a Psychic Pokemon (possibly Azelf or Alakazam), and you might want a Steel Pokemon (Steelix is a good choice). Or, a ghost Pokemon would work (Haunter/Gengar isn't a bad choice).

Other than that, do what you want for your team. But that's what I would do.

Well in your starting take a Chimchar which will grow in to a Infernape a good and very fast fire fight pokemon
Then catch the mighty Shinx which evolves into a very cool Luxray
Then take Geodude for a temporary Pokemon which you should replace with a Larvitar once you obtain the national dex go to route 207 and use pokeradar
Then you should take a Zubat and then evlove it into golbat feed it berries which make your Pokemon frendlier to get a super fast Crobat

A Abra for temporary which you should replace with Giratina you can catch it in Turnback cave but don't worry about it now
Now catch a Golduck which is a Versatile good Water Pokemon DO NOT REPLACE
Then take a Ponyta which evolves into a Rapidash
And take a Bibarel super useful wen it comes to HM's

Dont worry one bit because every trainer will know what to do