is there a way to download ds or gameboy games and stuff to your computer then play them on your computer instead of a ds or gameboy?

I know it's possible.
Friend of mine does it, but I don't know how to do it.
You'll need like an emulator I believe

yea im pretty sure all u need to dl is the pc version of the like what ever emulator u want

is easy

go on google.

for the gameboy emulator i suggest you Visual boy advance

for the ds emulator i suggest no$gba which is the best at this time.

then u type for the game u want
ex: Game name Rom