I wouldn't say Outrage, reason being is that you're only going to use it when facing Dragon-types; an Ice-type move will irrefutably do a better job regarding coverage. If you absolutely needed a Dragon-type move, Dragon Rush is the way to go in Rhyperior's circumstances, although it seems you would have to start again. Bearing THAT in mind, I'd then go for Dragon Tail.
Moving onto Aqua Tail; it's not too shabby. But Stone Edge and Earthquake will cover the types you're planning to use it on - in light of this, an elemental punch would be nice, e.g. ThunderPunch - it should function well when facing Water-types that plan to use special attacks that will take advantage of your low Special Defense and as you're aware, there are a plethora of Water-types out there; it's something worth thinking about. Fire Punch is a close second (regarding Grass and Ice-types), but I personally feel ThunderPunch is the most beneficial of the elemental punches, due to the fact your Megahorn can cover your Grass weakness. Shielding yourself whilst synchronously taking normally resistant Pokemon out would be lucrative on your part.
But yeah, in sum, I wouldn't recommend any of the moves you've listed, but more an elemental punch.