I'll happily jump on this train.
Gen 1: Charmander. You gotta love that powerful Charizard
Gen 2: Totodile. Bayleef may be the cutest Pokemon there is, but Feraligatr over Meganium.
Gen 3: I love all of them, but as you have heard: I do like Mudkips.
Gen 4: Turtwig
Gen 5: Probably Oshawott. Worst set of starters there is
Gen 6: Chespin
-I always catch a bad Normal type in the beginning that works as an ok fighter at first, but as a HM slave later on >: D
-Can't have a complete team without a bulky Steel/Rock/Ground type. Might use those for Strength or Rock Smash if I have to.
-A team without a powerful Flying type is a nono!
-I like to stock up on healing items and nothing else.
-I used to make a full team to help me through the game, but if I don't care that much I'll very easily end up with just one strong Pokemon + the legendary. It usually is the starter that I just level up like crazy.
-Reborn is the first game that made me use a team of over 6 Pokemon
-I always hesitate to challenge the leauge no matter how strong my team is. I don't know why.
-My team should be finished before the 6th gym