The runaway success of “Pokémon Go” should have taught Nintendo the value of having the right friends.

It is a lesson the company will need to keep in mind as it prepares to launch a new console in the hope of reversing its long-running decline. The Nintendo Switch, unveiled last week, is a unique marriage of a hand-held and home-based console. It features its own portable screen with controllers that can be plugged into a larger TV set and played like a more traditional videogame. The Switch is due to go on sale next March.

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