My Blastoise, from Blue, which is almost 11 years old and still active against my friends in Silver. Other level 100 pokemon I have are Arcticuno, Ho-oh, Pidgeot, Dragonite, Alakazam and Houndoom. The amount of 100s I have should probably be more, considering I've got quite a few pokemon that are over a decade old (making them older than 4 of my cousins, which is freaky as fuck), but I have a lot of pokemon that are 80+.
I have red, blue, gold and silver (and my brother's old GBC as well as my own), so I can restart games and keep old pokemon by trading them for rattatas and pidgeys. This gives me an advantage over most of my friends (we all still play 2nd gen against eachother, because we're old skool) with my awesome rolling line-up.