For every exception there is a rule...
Tilted orbits of Mercury and Pluto.
- Mercury probably suffered a large impact late in its formation
- Pluto might be a left-over planetesimal.
Retrograde rotation of Venus:
- Probably due to a large impact late in formation.
- Probability favors, but does not require, rotation in the same direction as the orbit.
High axial tilt of Uranus and Pluto:
- Also likely to be due to a large impact
- Also, in the outer solar system, computer models suggest the nebula was less concentrated in the plane, which could result in large tilt of sub-disks.