How to Get 99 Rare Candies in "Pokemon Yellow Version"by Lindsay Howell ; Updated September 22, 2017
A glitch in Pokemon Yellow allows you to get 99 Rare Candies, which will raise a Pokemon's level by one. You can take advantage of this glitch without having to use a GameShark or Action Replay. All you need is to have a Rare Candy as the 6th item in your Items pouch.
Move your Rare Candy to the 6th position in your Items pouch. The easiest way to go about this is to deposit six items into your PC box, including the Rare Candy. Then take them out again with the Rare Candy being the last item you take out.
Fly to Cinnabar Island and Surf up and down on the right-hand side of the island. You will encounter Pokemon that are level 100. Just run away from the wild encounter.
Continue to Surf until you encounter a wild Pokemon that is level 0 or level 1. KO that Pokemon, then head back to land.
Look in your Items pouch. You will have 99 Rare Candies.