No such as a Ultimate Defense. Each defense has some weakness. Examples: Gaara defense broken when it come in contact with Water, Neji weakness is when utilizing Eight Trigrams Palm Rotation technique, it is only effective when rotating, since the chakra itself is not enough to stop a physical attack thus if they cannot spin, the user becomes vulnerable. This was was shown in the Kidomaru fight. Susanoo weakness:
1. The user can be thrown out of the upper half of Susanoo by an enemy manipulating the substance underneath Susanoo.
2.The only known ways to attack the user while Susanoo is active is either to draw the wielder out of the technique and then attack,[6] bind and restrict its movements, or to break the defence with overwhelming force.
3. Susanoo users are also vulnerable to attacks which don't actually deal physical damage to it, such as strong lights and sounds, that can also impair their ability to sustain Susanoo.[7] Sound-based genjutsu can also bypass Susanoo's impressive defence.[8]
~ Wiki (I didn't feel like looking through Manga)