Charizard was my first one. It was in FireRed and my neighbour who had Emerald and a link cable asked me to battle him. I went back home and trained my Pokemon like a mad man until 3 in the morning. Charizard got to level 100 while all the others remained in the 80s.
We had our battle on the next day and I won even though I didn't get to use my Charizard in the battle much. :x