For 720p, you could chose just about any dedicated GPU you can get your hands on, and it'll do it what you want. No need to make a fuss over that component.
If Brawl is your main focus, and the MKs less so, an i3-4130 will do (some slowdowns will still be present in MK Wii mainly), and the Pentium Anniversary will do whatever you need it to do, most likely. So take your pick. For a price difference of < $20, you could bump it up to an i3-4330 for an extra 100MHz and a stronger IGP (which will definitely do SSBB at 720P, shouldn't have trouble with MK Wii, at least not often). Not bad if you ask me.
If Brawl is your main focus, and the MKs less so, an i3-4130 will do (some slowdowns will still be present in MK Wii mainly), and the Pentium Anniversary will do whatever you need it to do, most likely. So take your pick. For a price difference of < $20, you could bump it up to an i3-4330 for an extra 100MHz and a stronger IGP (which will definitely do SSBB at 720P, shouldn't have trouble with MK Wii, at least not often). Not bad if you ask me.