been testing SD cards. my finds..

[skrapps914]

i have a 16gb lexar card, non UHS. and it will give me a kernal panic when inserted via gameboy cart mod.
however it works fine when inserted into the pi0 itself.

I then went and bought a 32gb, sandisk ultra plus microsd card, with UHS 1. works perfectly in the gameboy cart mod and the pi0.

upon reading up on UHS, to my understanding, non UHS cards will have trouble reading through longer wires/circuits.

so, if youre having trouble with a kernel panic in the gameboy cart mod, try switching out for a UHS compliant microsd card.

[Kilren]

This might possibly be helpful:

SD Card Compatibility List