Not died, their focus just moved to japanese audience only. Temporarily. And it is also have their pro side since the YW 4 is more related to japanese culture. The efforts to gain the US audience contaminated the third game with westernizations. Also a good game but Yokai Watch should keep being a way to japanese culture experience inside games
Well I did make a list while going through for all the S ranks beyond 40,000 Yards while going through the tunnel many times. Here are all the Yo-kai you are able to befriend via overworld encounters: Statiking, Auntie Heart, Frostail, Devourer, Count Cavity, Kingmera, Damona, Shadow Venoct, Tigappa, Unikirin, Mermother, Swelterrier, Eyellure
You can get him in the past crank a Kai with a Brave coin or 5 star coin as well you can encounter him in the Infinite Tunnel. He can spawn by himself or be one of Yo-Kai with Auntie Heart’s encounter in the tunnel.
No matter what you do never interact with the switch or get on the train. As well make sure you are very very careful to choose the Longer option when talking to the building dude.