Nintendo may not have anticipated the astounding success of "Pokémon GO," since aside from server issues with the game, observers note that the accompanying wearable "Pokémon GO" Plus has also gone out of stock in some regions.

According to Forbes, the Nintendo Store currently lists the wearable as "Temporarily Unavailable." This already spells unprecedented success for both the game and its accessories, since the list for the wearable is only for pre-orders. "Pokémon GO" Plus is expected to fully release later this month.

The industry follower also notes that with the stocks depleted, some hardcore players turn to third-party sites to get the Plus wearable. However, since "Pokémon GO" Plus is admittedly in-demand particularly to hardcore "Pokémon" fans, some lists the wearable with exorbitant prices. In eBay alone, there are listings of "guaranteed delivery" for the wearable costing ten times as much as its pre-order price tag of $34.99.

While "Pokémon GO" Plus is not essential to playing the game, it does add convenience for "Pokémon GO" players. The wearable acts as notifications add-on for the user and it vibrates and flashes when there are game-related feedbacks such as nearby Pokémon in the vicinity, Gyms and PokéStops, and other in-game notifications. This means that players will not need to have their eyes glued on their phones all the time.

Meanwhile, aside from the wearable being out of stocks, other reports spell out Nintendo and developer Niantic may have been a bit overwhelmed with the release of the full version of "Pokémon GO." Although there was a beta test for scattered regions, the full release of the game still fell short days after it rolled out. Reports of servers being busy, if not entirely down, continue to make their rounds online. Meanwhile, the game still hasn't reached its full global release, as "Pokémon GO" continues to be unavailable in some regions.