They are also exceptionally rare, and there are only 3 in the entire game:
Pink Cloud Caves Deep Darkness Lumine Hall
Rock Candies don’t drop from enemies, so if you use all 3 then I’m afraid that would be your lot for the whole playthrough. Fortunately, there’s an interesting glitch that results in infinite uses of a Rock Candy. By using this method, you can completely max out the stats of your entire party. This guide will list the locations of all 3 “vanilla” Rock Candies, as well as details on how to activate the infinite Rock Candy glitch.
The 3 Rock Candy Locations
Candy #1: Pink Cloud Cave
Your first opportunity to obtain a Rock Candy is inside Pink Cloud Cave. This cave acts as the 6th “Your Sanctuary” in Earthbound. To reach Pink Cloud Cave, you must have first obtained the Carrot Key in Magnet Hill. Return to Dalaam with the key, and use it on the rabbit statues to the southwest. Once inside, climb up the first 2 ropes. Drop down the only hole once you’re at the top. Proceed all the way to the left, and drop down the hole at the end. You’ll land in a cave with the Rock Candy to your left.
Candy #2: Deep Darkness
You’ll arrive here via Submarine from Scaraba. Deep Darkness looks large and daunting, but it is actually fairly linear. The only time you’ll encounter branching paths is when they lead to treasure. From the entrance, you’ll make your way south and then west. Move left past the helicopter wreckage, and then take the first path north. From this fork you should go north again and the treasure here will be the Rock Candy.
Candy #3: Lumine Hall
Lumine Hall acts as the game’s 7th “Your Sanctuary”. You won’t be able to access this location until near the end of the game. You’ll first have to get the Book of Overcoming Shyness from the Library in Onett. Take this book back to Tenda Village, and show it to the chief. Next, talk to the Tenda near the rock in the southwest of the village. This will uncover a rope to a room below. Then talk to the big rock and enter Lumine Hall to the left. Lumine Hall is a massive area with tons of branching paths. Luckily there’s a fairly simple route to the Rock Candy. When you first arrive, make your way all the way to the north/northeast. Take the only ladder you see here. In the area below, make your way past the talking rock to the south. As you arc back to the north, take the first path west. The treasure chest here contains your 3rd and final Rock Candy.
Infinite Rock Candy Glitch
Now for the interesting part. To trigger this insane glitch, you just need 2 things: Sugar Packets can be purchased in Twoson, Fourside and Scaraba – whereas Delisauce is purchased in Dalaam. Here’s what you need to do: Step 1: Place the Rock Candy in the very last slot (bottom right) of a character’s inventory, while also filling the other slots with any amount of the other 2 items. Step 2: Get into a battle and use the Rock Candy on a party member. Instead of using the Rock Candy, a Sugar Packet/Delisauce will be used in its place. There is no limit to how many times you can do this in the same battle, providing you have condiment items remaining. Just be careful not to accidentally use up your Rock Candy outside of the glitch. And really, the only downside to this glitch (other than trivializing the game) is that your stats cap at 255. If you use this exploit on a capped stat, it rolls over back to 0.