Cinnabar Island: Aftermath
Cinnabar Island is an event-related location which has the sole purpose of providing the player with an opportunity to capture the Pokémon MISSINGNO after obtaining the Cinnabar Ticket from Mystery Gift. Because the island is strictly yet another reference to the infamous Missingno glitch of Pokémon Red and Blue, all other features corresponding to the Cinnabar Island of the main series of games have not been implemented.
Shortly after exiting the ferry landing, the player hears a cry for help somewhere else on the island. As the player progresses further, this person is revealed to be the Kanto Gym Leader Blaine, who is attempting to stop a mysterious Pokémon from corrupting the rest of the town. After the Pokémon causes Blaine to disappear, the player will be able to interact with the Pokémon, revealed to be MISSINGNO, and also be given an opportunity to capture it. After the player has finished with MISSINGNO there is nothing left to do except return to the ferry.
As stated above, interacting with the mysterious Pokémon grants the player an opportunity to capture MISSINGNO. MISSINGNO is encountered at level 50.
TIP: Save before fighting MISSINGNO, as you will not be able to fight it again if it faints in battle. MISSINGNO is also an extremely frail Pokémon, therefore any Pokémon or Attack Box capable of using False Swipe is extremely useful. Just watch out for its Glitch ability, as it will cause any Pokémon that makes physical contact with MISSINGNO faint immediately.
FACT: The MISSINGNO IS A FROGADIER THAT IS LVL 50