Okay, so technically, this was way back in my brother's Gold version...
The thing was, we were too young at that time. When he received the Spearow, he had no idea what to do with it. He couldn't remove it from his team either, since he can't remove a Pokemon with mail from his team...
He already had a Fearow at the time, so in the end, he had to travel with that bird... without training it... to the point that he reached the Elite 4, and became champion.
From then on, we dubbed it the legendary spearow for ending up in the Hall of Fame =w=
It was only post-game that he finally got rid of it XD