Check out the FreePascal forum for a discussion about using FreePascal for GBA development.

As for GC development, that's a lot more difficult. I do game development for consoles and the process of getting a game onto a console is quite difficult. We use specialized versions of C++ compilers to build the executables and then you have to link with the console-specific libraries. These libraries are only available to registered developers.

There is some homebrew development going on for consoles, but they are nowhere near the point where they could release a game.