PS2 and Gamecube emulation require really high single threaded performance, so AMD isn't the best choice for those, and the people making the emulators would recommend an Intel CPU. As said above, the FX CPUs aren't an option as they don't have integrated graphics, some AM3+ boards do have an integrated graphics chip, but it is really weak and not really fit for any sort of gaming.
The AMD A10 APU has the best integrated graphics available at a cheap price point, but its CPU performance isn't anything to write home about. It will be okay for most games, though you really would need a dedicated graphics card to play modern titles well. Emulation performance would also suffer due to AMD's cores being about 40% slower than Intel's.
What is the total budget he has, and what sort of newer games is he interested in playing? If it's really low, like $300 and he wants to play Witcher 3 for example, then there probably isn't much he can do without saving up more money unless he wants to start looking at used hardware.