I can't really remember what it officially became after the Elite Four. I definitely remember my Kabutops though, because prior to 100, I tested him and he seemed impervious to everything except grass. Then at 100, he gained a weakness to everything, including Water. Was a really bizarre thing, but I kept him around because his stats were still somewhat really good at the time. (Maxed out his attack stat at 328 during an unbreedable era!)
final result of team at E4 (i never change team members out in my plays except for removing the "trash captures")
Charizard Dragonite Dewgong Pidgeot Raichu Venusaur (i believe it was a pain finding someone with a gameboy to trade with) --- "All your sweetrolls are belong to me." Video play throughs at - http://www.youtube.com/user/DreadArkive
Blastoise (first starter) Pikachu ( the only pokemon who is always in my team) Nidoqueen (TM pumped) Starmie ( Water pokemon are the best) Simsala (Trade with someone, i gave him my graveler) Last i can't remember --- Fighting games needs more Pikachu!