Which Team To Choose
The most influential decision a player must decide upon in Pokemon GO is none other than which Team they should become apart of any where after their trainer reaches Level 5. Some people like to follow their heart with this choice, usually involving what the team stands for or the Legendary Bird they are associated with, but that's usually not the best, most competitive move one can make.
Here are some tips on which team you should choose:
1) Join the team that dominates your area. It will allow you to build around the Gyms your Team already owns, as well as save items needed to dethrone other teams at other gyms.
2) Join the team that has dominated the world so far: Team Mystic. Almost one half of Pokemon GO enthusiasts have chosen this Team of Blue and Articuno, and as the old motto goes "if you can't beat 'em, join 'em." At some point if you travel outside your usual area, you will see their dominance in gyms across the world.
3) Go against the grain and join a team that doesn't dominate your geographical area. It's the best option if you love to battle and want to earn your keep. Plus, those battles to claim gyms also help you gain more XP.