Just wanted to leave a post to say that the 8bitdo Arcade Stick works great with Bloopair. I downloaded and installed 0.5.0 as I have CBHC still and then paired the Arcade Stick as a Switch Pro Controller via Bluetooth - worked right away once I ran Bloopair and pressed the sync button. Does not need to be repaired either once you've turned the Wii U off, just run Bloopair again and had to the home menu and turn on the Arcade Stick.
I did this to use the CrazyMac build of RetroArch which is packed full of my favourites. To get it working, you need to had to Input, then choose User 1 input index as "Wii U Pro Controller" and load up a game. In some cores, it does ovverride this setting so keep the Gamepad close, hit the home buton to get to RetroArch menu then go through the above steps, but also be sure to make controller 2 port empty as otherwise you will end up controlling two players from one controller. Bit finicky and I'm sure with a newer version of RA (CrazyMac 2.0 is old on 1.7.7) I wouldn't need these steps, but having the GamePad close isn't much of a problem.