You can play all GBA games on the DS. Additionally, there is a follow-up to the Boktai series on the DS called Lunar Knights. It's actually Boktai 4, but we never got Boktai 3 and Konami might have been afraid of the brand recognition of 'Boktai' with 'dumb solar sensor'. You can use one of the GBA Boktai games with Lunar Knights to use the GBA's solar sensor for Lunar Knights.

Also, the Solar Gun from the Boktai series is in MGS4 :P