Pokemon HeartGold & SoulSilver launched over a decade ago, yet fans are still discovering fun bits of information in the game. A user by the name of Alucard the Hedgehog discovered that there is an NPC in Cianwood City that can give the player a Tentacool in case the player ever gets stuck.
For context, Cianwood City is a location in the game that is necessary to visit, but it can only be visited once a player gains the ability to use Surf. If a player were to travel to the city and then release any Pokemon that could learn the move, the player could theoretically be stuck on the island with no way to progress. Alucard the Hedgehog was determined to softlock his game and get stuck on the island, and in the process, he discovered that an NPC will appear if certain conditions are met. Therefore, players can NOT actually get stuck on the island.