Robonyan in Yo-kai Watch 2

Robonyan can be befriended automatically in the quests Watch the Skies (which can be activated by speaking to Toiletta inside the Harrisville School after beating the main storyline) and From the Future! with the latter being exclusive to Fleshy Souls.

He can also be freed from either Crank-a-kai with Play Coins and the Destiny Oni Crank-a-kai.

He is required for a Baffle Board in the Abandoned Tunnel east and allows access to the waterfall area and gives you a Choccobar every 24 hours.