I actually use a Pikachu on my team on every game I've played since Yellow Version... It's kind of stupid but I use it as a homage to my Pikachu in Yellow and to never forget what got me into this in the first place.
Only time I've used something different was a Raichu on Pokemon X (since I had already beaten Pokemon Y with my unevolved Pikachu). Plus, it's great to hear Pikachu saying its name again on X&Y! --- 3DS Friend Code: 5069-4038-9443 Friend Safari: Ice Type
My sister made it her mission to run around in Santalune Forest until she found one on release day. I believe that first one she caught had a Light Ball. My cousin also decided to use Pikachu after she stopped playing since Gold... although I'm pretty sure she boxed it so she could use a Dratini that I traded her. --- 3DS FC: 5370-0398-2889