When starting up the game at first time, and have answered the questions about your personality, You find out which pokémon you are. Then think twice before choosing your partner. If (as i did) became a Chimchar) Then i would never choose another Fire-type pokémon. I've choosed Pikachu, but i really should have taken Squirtle. Fire and water. If it is a team together it is a good combination.

Also when you choose your partner, there will only be shown 8 pokémon's, but if you only select one of those and then say no to this, then will about the half of them be replaced by some others that you can choose too.

At last a good tip. Read all information and all text, everything twice. There can be some kind of VERY GOOD information in it.