If a kof game doesn't have a Bullshit boss it's not kof.
But I think I heard that after you beat the game you unlock the boss, probably like saiki? Didnt you have to beat the game to unlock him? And then like, shin Akuma as the boss and just had a snack Akuma as playable?
Imo Krizalid in kof99 was hard without being overpowered.