Fighting games were scarce on the 64, but MK TRILOGY was a really good one for it.  It took all characters from all 4 MK's (Mortal Kombat, MK II, Mortal Kombat 3 and Ultimate Mortal Kombat 3) and also made some of the bosses playable characters like Goro and Kintaro.  More or less, all of the characters that have been in the game this whole time (ex Liu Kang, Shang Tsung, Scorpion and Sub Zero) were the Ultimate Mortal Kombat versions.