I don't think you can compare defensive SF Hippo to Landorus-T and Donphan. Landorus-T is a tank that's suppose to hit hard and work more as a pivot, while Donphan is used for its utilities. Hippowdon, however, is a completely different animal in the fact that it's there to wall and phaze things. It has reliable recovery, which completely sets it apart from Lando-T and Donphan (and Gliscor as well). I know Hippowdon is mainly used for Sand Stream, but it wouldn't hurt to at least mention how Hippowdon can be used outside of sand teams using the same set, except without Sand Stream.
Whatevs sig. QC member for OU and Ubers, VM me for a look at your analysis. Just make sure it's good.
Also, if you want me to rate your team (OU/DW OU/Ubers), give me a VM. If I don't rate it, it's either 1) it's so shit it's too much trouble, 2) I'm busy, or 3) the team is fantastic and I have nothing I can suggest to you. You should be able to recognise which one.