+2 252+ Atk Life Orb Gallade Knock Off (97.5 BP) vs. 252 HP / 252+ Def Gourgeist-Super: 367-434 (98.1 - 116%) -- guaranteed OHKO after Stealth RockNebuchadnezzar, the point of suspects is to remove unhealthy components of the metagame, and not all metas immediately suspect another mon the moment their current suspect ends. Between the ORAS Megas, ORAS tutors, the release of certain hidden abilities, and new (or old) comers to the meta, be it tiershift or quickdrops, NU has kind of been in a state of unrest and never really settled down, so the suspects are sort of urgent. There is really nothing wrong with suspecting mons in quick succession if the meta isn't currently in balance due to overpowered threats, or some elephants in the room just need to be rid of.
Tomahawk you forgot Gourgeist. Still, I don't think it is too practical for SD Gallade to carry Poison Jab (it's probably more suited for CB Gallades), nor is it fair to not list Colbur Psychic calcs; though that said, Gallade could do significant damage with +2 boosted Knock Offs against Colbur, or just +2 unboosted Knock Offs.
To be honest I feel like SD Gallade can use anything it wants, Swords Dance / Close Combat / Knock Off and the last slot is completely open. Use Zen Headbutt if you don't want to get stopped by Poison-types, use Shadow Sneak if you don't want to be stopped by Fletchinder. Are you using a team with something that really benefits the removal of Quagsire or Fairy-types? Use Leaf Blade or Poison Jab respectively. It has a lot of viable options for that last slot to be honest.
And I suppose, but I don't see Musharna or Uxie using Colbur, maybe that'll change though because of the prominence of Gallade and Sneasel. Here is a calc versus Mesprit:
+2 252+ Atk Life Orb Gallade Knock Off (97.5 BP) vs. 4 HP / 0 Def Colbur Berry Mesprit: 281-331 (93 - 109.6%) -- guaranteed OHKO after Stealth Rock