Peter Griffin Vs Sakura
Homer Simpson Vs Peter Griffin
Ryu Vs Peter Griffin
These were all made using the Mugen engine.
M.U.G.E.N is a freeware 2D fighting game engine designed by Elecbyte, written in C with the Allegro library. The engine was originally released in July 17, 1999. The engine allows anyone to create characters, background stages and other game objects through interpreted text files, graphics, and sound compilations.
Also, heres a link to the Family Guy Vs American Dad Kung-Fu Flash game Link