I actually remembers this show from my childhood. Airing exclusively on the USA Network's Action Extreme Team block alongside cartoons like Street Fighter and Savage Dragon, Mortal Kombat: Defenders Of The Realm is based on the controversial video game franchise best known for having gruesome Fatalities done on sprites made by digitized actors, which would be one of the factors that would lead to the ESRB ratings board being created.
So basically, this cartoon world be controversial, as it is based on a game series that is rated Mature. However, to get past this, the creators decided to make this cartoon a sort of sequel to the first Mortal Kombat movie. After Shang Tsung's defeat at the hands of Liu Kang, the dark forces of Outworld have begun invading Earthrealm, weakening its dimensional fabric to the point where invaders from other dimensions are also entering the realm. To protect Earthrealm, Liu Kang, Sonya, and Kitana (Johnny Cage is not in this cartoon, and while he was killed in the events of UMK3, this cartoon never mentions him or his possible fate) forms a team of other warriors to combat these threats.
So, this cartoon takes the heroic characters of the games up to Mortal Kombat 3 and puts them in a team similar to G.I. Joe. Some of the characters are even redone to have roles (like Nightwolf, who is normally a shaman, being cast as tech support, although he does join in some missions, even having a wolf he can merge with to increase his powers, and Sonya as the hot head who rushes into battle without thinking.) As it's set after the first movie, it has some flashbacks to events of the film, although said flashbacks are redone to make them kid-friendly (the older Sub-Zero's death is changed from being impaled by an iceberg to being frozen completely solid). Also, the characters use their special moves, while Fatalities are non-existent, save for Sonya's Kiss of Death (which no longer burns an opponent, but knocks them back like any other projectile).
Despite that, the show has some flaws. Mainly, the voice actors are hit-or-miss (I do like Stryker, who is voiced by Ron Perlman, but Sub-Zero's VA sounds like he does not fit the former Lin Kuei-turned-Defender), some characters being one episode throwaways (like Scorpion, who nowadays, is the face of Mortal Kombat, but here, he only appearing in the second episode and was made one-dimensional), and stupid one-liners (like Sonya's battle cry being Kombat Time). However, this has some memorable moments, the best one being the episode that introduced Quan Chi, an evil sorcerer who after this ended, would go on to appear in the games as a primary antagonist. It's an okay cartoon, but not something special.