Well, the way I see it, is that your strategy revolves around you avoiding fire breath, but hitting with plasma breath. What that's basicly saying is avoiding your opponent's attacks and hitting with yours.
Also, if they're both firing beams, why does Rayquaza, who is comfortably on the ground, tire faster than Ridley, who must make sure he stays airborne. You also have said that when Ridley eventually lands, he is vulnerable. Obviously, Ridley must land eventually, if only briefly, and is most vulnerable there. Ray is most vulnerable from the plasma beams, and again, this assumes plasma beam hits and flame doesn't.
EDIT: @KingCobra - We've already established that Rayquaza cannot fly.
Primarily because Ridley's gliding mobility is both superior, and less predictable. I posted the vid of how snakes move, and while it can be fast, it's VERY easy to predict their movements.
I'm not talking about tire in the sense of over-exertion. I'm talking about tire as in battle wounds, aka, being continuously cooked.
The flame will hit sometimes, but it's less powerful, so it's less damaging, and the mobility advantage means that he'll be unable to continuously keep it on Ridley whereas due to Rayquaza's lesser mobility and more predictable movements Ridley will be able to keep it trained, which means overall Rayquaza will tire from battle wounds well before Ridley. He wins the war of attrition basically.
So yes, I'm saying that Ridley has the tools to hit with his attacks a lot more and a lot harder, and gradually win the war of attrition, assuming that he doesn't get grabbed or something. Yes, he's very vulnerable when he lands, actually attempting to force him to land in certain areas is probably the best use of Fire Breath.
Yes he will be hit with fire breath, but it won't be continuous barrages (which is where the real issue is).
Again, it's all about the tools that characters have in match-ups, and mobility is a very important one.
rayquaza flying is possible by spinning his little rudder things he propels himself
Lol, show me a piece or technology or better yet, an animal that can actually do that and we'll let rayquaza fly.
Since that's what the move Toxic is shown to be (spitting poison), then yes, he can.
Rayquaza's thick scales would offer a degree of protection from Ridley's plasma breath.
Rayquaza's body is both flexible and able to move quickly, so he shouldn't have too much of a problem dodging.
Pokemon animations are very generalized, I don't see him with any other poison moves, so it doesn't really stand to reason that he'd have delivery system built in for a move that he doesn't even naturally learn.
That said honestly, unless he can make it encounter blood or soft tissue, it's useless anyway. Ridley's scales would protect him from spit poison anyway if it was spit. Best delivery system is the bite anyway.
True. That's why it's a war of attrition.
On the ground, for snakes to move anyway, the have to do a good amount of preparation, except the extremities. Again, I posted how a snake moves earlier, this shows that on the ground, it's a very different story. Being grounded hurts Rayquaza a lot.