Can M-Ray survive without a Dragon STAB?

I am planning among entering the Generation Showdown, and amongst my slew of potential Pokémon is Mega Rayquaza (who won’t be using him?) and I’m having troubles with his moveset. Here’s what I have planned:

Rayquaza@ Life OrbAbility: Air LockEVs: 252 Atk / 252 Spe / 4 DefAdamant Nature- Dragon Ascent- Dragon Dance/Swords Dance- Extremespeed- Waterfall/Dragon Claw

The plan is to bring Rayqauza to almost every fight. I’ll Mega Evolve him when necessary and restrain from Mega Evolving if it is not, so that I can use another Mega. I am having difficulties, however, on deciding the final move. Does M-Ray evenneeda Dragon attack for anything other than opposing Rayquaza, which I already have answers to? It only covers Dragon, and Dragon Ascent hits so rediculously hard that I believe a Dragon STAB is unnecessary. I also have to choose between D-Claw and Waterfall, and I would rather have Waterfall to handle Primal Groudon, who is likely to be the second-biggest threat in the competition other than M-Ray. Can Rayquaza get by without a Dragon STAB, or should I replace either ESpeed or Waterfall for it?

Pleaselog inorregisterto add a comment.

RunSwords Dancein conjunction withEarthquakeover Waterfall to hit Primal Groudon. It gives the added ability to demolish pokes like Aegislash. Assuming Primal Groudon switches into you and nullifies your Delta Stream, you will still be able to hit Primal Groudon without the need to cancel out its Desolate Land with Delta Stream.

“If Delta Stream is suppressed or replaced, the strong winds it causes will disappear. If another Pokémon in battle has the Ability Desolate Land or Primordial Sea, the dominant weather condition will be determined by whichever Ability activated last."-Quoted from Bulpapedia

Oh and by the way:

This is assuming an Adamant Nature. You miss out on this OHKO if you run Jolly, but Im not sure how relevant it is, as most Primal Groudon dont run 252HP/252Def anyways.

This leaves you walled by Skarmory, but it cant do much other than whirlwind you out while taking an enormous amount of damage from Dragon Ascent anyways.

Oops, I dont think it walls…

First: Run SD.Second: Run Jolly. You’ll be able to Speed tie with other Mega Rays or outspeed them.Third: Yeah, I’m pretty sure you can live without a Dragon STAB. Dragon takes out other Mega Ray and Mega Mence, but P-Groudon is probably gonna be a bigger threat. Water/Flying has better neutral coverage.

Final Verdict: Use SD, Run Jolly, and Use Waterfall.