Before searching for a ROM, you must understand exactly which game you are looking for. Yo-kai Watch 4 launched in June 2019 exclusively on the Nintendo Switch (and later PS4 in Japan). However, Level-5 released a massive updated version titled (pronounced "Purapura").
Gorgeous art, but play on PS4 or Switch docked if possible.
To unlock this mode, players must complete Quest No. 50: GOGOGO from the bottom of Hell! , which starts in Chapter 7 with Poofessor in the Past Yo-kai World.