Guillotine, Sheer Cold, Fissure and Horn Drill are all really bad moves. The accuracy is calculated by level, i.e. if you're the same level as your opponent, the chances of hitting are 30%. The higher level you are than your opponent, the better chance of it hitting.
By the time you're high enough level for those 4 moves to have decent accuracy, you're so overpowered that using any damaging move would OHKO your opponent, negating the point of having any of those moves.