I've had a few Level 100s; Typhlosion (Crystal), Feraligatr (Silver), Mew (Traded to Silver at level 7), Mewtwo (Blue/Leaf Green), Charizard (Blue/Leaf Green), Tyranitar (Crystal/Leaf Green), Heracross (Crystal/Silver), Scizor (Crystal), Raikou (Crystal), Snorlax (Leaf Green) etc.
It's a pain in the ass raising them, but it's well worth it in the end.