The shader appears to be wrong, and making real time lighting on the 3ds is expensive. You might want to go the pre baked light path.
In case, you can use mobile shaders to fix this but i am unsure if it supports real time lightning
so, is developing with unity on the 3ds still really taboo? because i have been beating my head onto it for a bit and it wouldn't make sense to create a game without the ability to share anything about it