Mortal Kombat Deception is the first mortal kombat to officially feature online multiplayer and was played competitively online it was featured at evo 2005 on the main stage and has been hosted at locals back in the day. Me in my friends would practice to try and beat the top players online.
characters: This game included , Kenshi, jade, scorpion, mileena, sub zero, baraka, havok, sindel, raiden, hotaru, kabal, ermac, nightwolf, bo rai cho, noob/smoke, tanya, shujinko, li mei, ashara, dairou, kobra, darrius kira, liu kang.
This was the roster for ps2 and xbox, more characters were added in other versions. In theroy there a lot of "unplayable" npcs you could fight as if you had a gameshark or action replay to hack the game but the base roster is all i've seen in competitive play.
game versions
ps2/xbox:
This was the version played the most, online play is what made these versions the standard despite the smallest roster.
gamecube:
This version decided to accommodate it's lack of online play with two bonus characters exclusive to gamecube, goro and shao kahn
psp:
This version of the game titled Mortal Kombat: Unchained was released in 2007 with all the characters from the gamecube version and kitana, blaze, jax, frost. This version also had online play. Although this game hasn't been played competitively by many to my knowledge it's an excellent version, it was released on the psn store for vita as well.
Notation
1 is light punch (square on playstation, x on xbox)
2 is heavy punch (triangle on playstation, y on xbox)
3 is light kick (x on playstation, a on xbox)
4 is heavy kick (circle on playstation, b on xbox)
blk is the blocking
throw is your characters throw
h2h your fighting styles which involves your fists.
weapon your last fighting style that involves your weapon.
CS the style changing button, some strings let you combo into it.