As the original S3K rom is 4MB, jEnesisDS has the limit of running <3MB roms.
To get it to work on jEnesisDS, use this patch.
Use WinIPS: http://fuji.drillspirits.net/winips/
to patch it to the clean Sonic & Knuckles (NOT Sonic 3 & Knuckles) rom.
This patch puts all the Sonic 3 stuff excluding the Competition/2 Player stuff in the rom.
As the Competition/2 Player stuff are excluded, selecting...
How to get Sonic 3 & Knuckles to work on jEnesisDS
To get it to work on jEnesisDS, use this patch.
Use WinIPS: http://fuji.drillspirits.net/winips/
to patch it to the clean Sonic & Knuckles (NOT Sonic 3 & Knuckles) rom.
This patch puts all the Sonic 3 stuff excluding the Competition/2 Player stuff in the rom.
As the Competition/2 Player stuff are excluded, selecting...
How to get Sonic 3 & Knuckles to work on jEnesisDS