There are emulators for the Mac that will probably play Pokemon

I have no idea what system Pokemon is for, what system it originally ran on.

Find the emulator, find the ROM, and you're good to go.

You can find software at VersionTracker.com

As for the ROM, you'll have to find that on your own as ROMs are a legal gray area and I don't want to cross the line here.

Hope it helps

P