Mario Golf N64 - Complete with everything in very good condition and comes with it's own box protector. 

Mario Golf Game Boy Colour - Comes with an official Game Boy Colour cartridge case.

These are some of the very few games that could be linked together through the Transfer Pak.

Both cartridges have had their internal batteries professionally replaced with name-brand ones (AKA; not cheap Ebay ones) and their contacts have been properly cleaned with isopropyl (70%).