I try. But, for my in game team, I basically just use guys that I like. I would occasionally switch them out. This gen however, there are so many awesome new Pokemon that I will be switching my team out often. My team will easily consist of over 20 different Pokemon with the strongest (and most diverse) being the ones who go to the Elite 4.
Xerneas, The DNAntler Pokemon Currently Awaiting...SSBU, SSB3DS, Pokemon X, Pokemon Y and Watch Dogs.