I already said this in the profile comments but i'll post it here for everyone
pokemon 3d is built on XNA, by microsoft, which is coded in c#. This means the game isn't that portable, it could maybe run on an xbox 360 but that is about it. To make a linux or mac port nilllzz would probably need a new engine.
If you have windows boot camped on your mac (assuming its one from after they started using intel cpus) you should be able to play it just fine. you would also need the .net and xna runtimes the game depends on (like 4 meg each), which are linked in the troubleshooting page in the launcher.
XNA is pretty much direct x so people on linux could maybe use wine etc? i am unaware of anything like that for mac because i don't have one. At least everyone can dual boot now, so while pokemon 3d doesn't support your OS, it at least supports your hardware.