Instructions
Beat the Crystal Castle boss by hitting the Army Dillo villain repeatedly on the head. Go to the key that appears after Army Dillo is defeated and press the "A" button. This is the first of K. Lumsy's keys that you need.
Defeat the Creepy Castle boss, Kardboard K. Rool, immediately after Army Dillo. Take the K. Lumsy key after you beat the Creepy Castle boss. Return back to the main beach of the island.
Find a tag barrel and turn into Tiny Kong by jumping into the barrel that has Tiny's face on it. Tiny Kong must first be unlocked by Diddy Kong in the Angry Aztec world.
Locate the Tiny pad and stand on it. Press the "Z" button and you will transport to the top of the island. Walk all the way to the front and go into the mouth-shaped cave.
Find a tag barrel and turn into Chunky Kong. Go to the Chunky pad in the mouth and stand on it. Press the "Z" button to transport to the entrance of the Hideout Helm level. Swing across the vines and make sure that you have 100 bananas to enter the level.