This page explains how to solve the quest "Fusion Time!" in Yo-kai Watch.
Start the Quest
Go into the Shoten Temple in Blossom Heights and talk to Mr. Zen to start the quest.
Get Yo-kai for Mr. Zen!
Mr. Zen asked for a Mochismo and Dulluma.
Mochismo can be found in Uptown Springdale in the area near the Fish Place, under cars and vending machines. The map will say "Fish Place" when you are in the right area. Mochismo likes rice balls, so be sure to buy some at an Everymart. When you encounter a Mochismo, before you tap Fight, you should tap Items, then choose a rice ball and tap "Use on Foe" to throw it at Mochismo before you attack. This will slightly increase the chance that Mochismo will befriend you after the battle.
Dulluma can be found in Uptown Springdale under cars and vending machines. You might also find him in The Catwalk alley or the Desolate Lane alley, both in Uptown Springdale. His favorite food is bread, so buy some from Banter Bakery. Read the previous paragraph for information about how to use the bread to try to befriend Dulluma.
Quest Complete!
When you have a Mochismo medal and a Dulluma medal, talk to Mr. Zen in Shoten Temple in Blossom Heights to complete the quest.