Sorry, Grey Test, I had to answer this since I am starting Rain Ubers myself.
If you are going ScarfOrge, Water Spout would a recommendation over Hydro Pump. I know it gets unreliable as your HP goes down, but it can land a KO to all but those who resist it. HP Dragon is kind of useless, you already have Ice Beam to destroy Dragons. Switch it for Hydro Pump (Both of them can be useful) or Surf, to be more reliabe accuracy wise.
You should definite invest EVs in Speed, even with Choice Scarf Kyorge will be outsped by many with out EVs in speed. A good +Spe Nature won't hurt it either.
Yep, Thunder Wave + Gyro Ball + Fail. Power Whip FTW xD. Other than that, great Ferrothorn, just consider Leftovers.
252 EVs in Speed. You need to be able to outspeed Pokes for this to be a sweep. So, 4 HP / 252 Atk / 252 Spe. Um, what item? Life Orb, Lefties, Choice (then rid of Hone Claws), many choices. If you decide or a choice item, then switch Hone Claws for Outrage. STAB at Band/Scarf is powerful.
Consider Scarf. I personally think Scarf works better, because many dragons will outspeed if you don't have it. If not, Specs works I guess. Maybe try Dragon Pulse, though Draca Meteor is great, too.
Leftovers. If I'm correct, only one move benefits you from the Orb. Dialga has execellent defense, so take advantage of that. Feel free to try out Dragon Pulse, again, not needed, just an idea. In Rain, abuse 100% accuracy with Thunder instead of T-Bolt. Otherwise, great Dialga.
IMO, Tentacruel is a little too frail to be in Ubers. Try this guy, Giratina:
Giratina @ Leftovers
EVs: 252 HP / 128 SpD, 128 Def
Careful Nature (+SpD, -SpA)
- Dragon Tail
- Sleep Talk
Also try out Arceus Steel Not going to make a moveset, Smogon's are great.
Just some suggestions, don't need to try them out if you don't want to. Hope This Helped :D