It was either Pidgey or Caterpie in pokemon blue. I remember how realistic I took it as a kid, I jumped up and down and my mom thought it was hilarious when I'd run in her room with my GBC and hold it up with one hand and announce like Ash did "I CAUGHT A PIDGEY!" Haha, wow was I young. Very good times. I owned everyone in my neiborhood, even kids older then me. I am glad my passion for it started young.