This list that I have compiled includes those bosses that stand out the most in any of the traits mentioned while bringing a degree of difficulty that will challenge and excite the player. Keep in mind that this list of the baddest SNK fighting game bosses in comprised of those games found in the NeoRAGEx 5.0 emulator. Also, this list reflects my personal OPINION on the subject and nothing more, anyone is welcome to disagree with any of my choices with proper context.
At the high point of KOF 97 the player must face four sub-bosses prior to facing the final boss named Orochi. Orochi Yashiro is the last and the toughest one to beat of all four. While many of his moves seem subdued and less impressive, Yashiro has an annoying way of sidestepping the player's attacks (a trait present in most KOF bosses). Coupled with his lighting fast attacks this sub-boss is quite formidable. What's especially unique about his design is that he's a grappler; and I can't think of any other bosses you use mostly grappling attacks at all. None the less his attacks are brutal to look at, especially the one where he grabs you by the head and whips you over in a mid-air body slam and then crushes you with his explosive fist, ouch!
Whoa what a freak! Grant appears as a sub-boss in a little known SNK game named Garou Mark of the Wolves. Anyone familiar with MAME might know it. Even though he isn't the boss of the game, Grant is one helluva boss design. Personally his brutish appearance only adds to his overall appeal for me; and once you start fighting him you'll quickly realize that this dude has a whole lotta power behind his attacks. Heck, in one move all he does is flex his chest and the opponent is sent flying. No really honest!
Ever thought of having your face kicked in to the tune of "I love the pit, pit patter of the rain drops"? Well I imagine that if he were real, Krizalid would probably do something like that. When you first face him he doesn't appear to be powerful. Any sensible gamer would reserve final judgment about him until they see what's coming next; and boy are they in for a surprise. As if it's not enough being thrown around with the bottom of a boot heal, the players character is subjected to all kinds of punishment including razor sharp cutting winds and flame attacks. And all the while with a wide grin on his face. I kept thinking after fighting him for the first time "You sick bastard".
Chizaru appears as a sub-boss twice in the entire KOF franchise. Her first appearance was tough but beatable in the KOF 96 game; the second appearance on the other hand in the later KOF 2003 game wasn't as lenient. When playing against for the first time in KOF 2003 I kept thinking "Doesn't she ever let up?" After a number of solid tries I discovered that using characters with good projectile range and careful timing was the easiest way to beat her. Nonetheless she is still daunting to defeat as she possesses the ability to attack with mirror images of herself. Oh and she has help from her weaker twin sister who can jump into the fight at any time to keep the player tied up.
This KOF boss just won't die. Seriously he's supposedly been killed in two other KOF games before making another appearance in KOF 2002. Compared to the other versions this one seems to me to be the cheapest of the lot. First of all he still has a nasty way of countering all you’re attacks with that slicing kick move that’s been amped up to juggle and opponent in the air for greater damage. Furthermore his Kaiser Wave projectile can be charged until it becomes unblockable. Beating Rugal wasn't easy before KOF 2002, now it just seems hugely unfair. In Jamaica a phrase that would best describe the player's lop sided fight against this boss would be, "A wad dis Fada?"