I always used two Pokémon; my starter, and the mascot of the game. That was back in my R/S days.
After playing Red Version and then getting Leafgreen a few years later, I decided to make a balanced team to overtop all typings, similar to Red's team. It then consisted of Empoleon (From my first Pearl file, started Christmas Eve, 07), Blaziken (First Ruby file, Birthday of '06), Serperior (First White file, Release Date), Pikachu (Dunno why, it's stats are horrible.), Staraptor (Same date as Empoleon, Shiny) and either Lucario or Zoroark.
Ever since, My team has been balanced. Until the arrival of me getting into online battles. Then I had to use Explosion Metagross, Focus Endeavor Starly, etc...