To get 100 of any item in your inventory, make the item you want the seventh in your inventory, do the following: 1. Fly to Viridian City and talk to the old man who shows you how to catch pokemon. 2. As soon as he is done talking, fly directly to Cinnabar Island and walk right in a straight line till you reach the water. 3. Surf directly up and down the very edge of the island, you may meet level 150 pokemon of different sorts, but keep on running and surfing until you meet someone called Missingno, or a name similar. 4. Run away and the seventh item in your inventory will have a funny symbol next to it, which means that you have more than 99 of it.