Not known to many Pokemon is actually a very hardcore strategy game. It requires you to invest hours upon hours to get the right stats for your defense, special deference, attack, special attack on your poke monster. On top of that to make sure that each pokemon can compliment the weakness of the next in your part of 6. Here are a few tips to help you out in competitive online battling.
First and foremost choose the pokemon with the highest base stats, the best way to lose a pokemon battle is to use pokemons which you like. Not all pokemon are made the same and there is a tier of overpowerd pokemon with base stats of 700 and pokemon that have a mere 100 base stats across the board. So choose wisely.
Second try to use megastones in your party. Mega pokemon where just recently introduced as the next stage of evaluation. turning that charizard into a mega Charizard. Try to have a mega pokemon in your team. You can only pick one though so choose wisely.
Balanced team: No team is perfect but you should try to make a diverse team of pokemon which compliments each other weaknesses and strengths. For instance dont make a full party of fire pokemon becuase if your opponent has one water type pokemin its open season on your team. follow these simple steps and you will become the very beast like no one ever was.