for me it works the first 10 seconds then it starts lagging. i use an HTC U11 with Android 7.1 and Bluetooth 4.2 i think the Android Version is to high on older devices it works.
Both of the joy con's are without any lag for about 2 seconds. After that it start to lagging.
I have a HTC u11 with 4.2 Bluetooth.
I have downloaded the app Bluetooth auto connect and set the joy con's to HID but I got only 2 seconds lag free.
@Xdqwerty, Osu! Tatakae! Ouendan! is the Japanese version of the game, different settings/characters/songs but otherwise identical mechanics. I played that before I knew about Elite Beat Agents lol. Both fantastic games https://en.wikipedia.org/wiki/Osu!_Tatakae!_Ouendan