For all five generations so far, I *HAVE* to start my game with 3 starters. I'll get one, trade it over to my sister, restart... and repeat. It's annoying that you need one badge now to trade, but whatever.
But yeah, I'll play through the whole game with my 3 starters, a flying type (for fly), and about 2-3 other Pokemon for HM purposes. Get my 8 badges after about a month of playing. Then once I beat the Elite Four, I'm usually done.. =\ I'll continue to play if there are daily things to do but they get old fast.
Rather disappointing really, especially in B/W2, with the Shiny Charm I thought I would be more motivated to finish my PokeDex but I just don't really care.
Anyone who supports DLC of any kind deserves a swift kick to the balls... repeatedly. Take a stand! Don't let companies take advantage of us!