(update 3)
EDGB OS v2Compatible SD Card:Any SD card is Spec version 1.01
*SDSC card
-512MB SD card has NO class ranking
-1GB SD card has NO class ranking
-2GB SD card need be Class 2 anything less than 2, will fail to load OS
Any SD card is Spec version 2.00
*SDHC (normal type)
-4GB SD card need be Class 4 anything less than 4, will fail to load OS
-8GB SD card need be Class 6 anything less than 6, will fail to load OS
-16GB SD card need be Class 8 anything less than 8, will fail to load OS
-32GB SD card need be Class 10 anything less than 10, will fail to load OS
Access Time need be 0.81ms or lower, anything more than 0.93ms, will fail to load OS(according to sd2snes' sd card page)
*"normal type" mean SD card without fancy label
Example
SanDisk (normal type) sd card will work fine 
SanDisk Ultra sd card will fail
Incompatible SD Card:Any SD card is Spec version 3.01 ("digital rights management" DRM Edition)
*SDXC
-SanDisk Gruvi (any size)
-SanDisk Extreme (any size)
-SanDisk Ultra (any size)
-Ultra High Speed (UHS) (any size)
-UHS Speed Class 1 (U1) (any size)
-UHS Speed Class 3 (U3) (any size)
-64GB SD card
-128GB SD card
Any SD card is Spec version 4.00 ("digital rights management" DRM Edition)
*SDIO
-SanDisk Gruvi (any size)
-SanDisk Extreme (any size)
-SanDisk Ultra (any size)
-Ultra High Speed II (UHS II)(any size)
-256GB SD card
-512GB SD card
-1TB SD card
-2TB SD card