The King of Fighters XIII/Saiki (Boss)
From Shoryuken Wiki, Marvel vs. Capcom 3 Strategy and More!
In a nutshell
The boss version of Saiki, which shall hereafter be referred to as EX Saiki, is the sub-boss of the game. He possesses an almost entirely different moveset than his unlockable counterpart. He has several different kinds of fireballs, for example. One of these types will encase you in what appears to be tar, and this can be spammed by the AI for an easy infinite. He also uses an annoying grab that wastes valuable time and does about as much damage as two special moves put together. He has no NeoMax, but the super that he does have, which is his playable version's NeoMax, does about 1.5x as much damage as that version, and comes out instantly. To beat this boss, one must have patience and learn to pressure him into the corner.