Have you ever used a Rayquaza Competitively or In-Game? If no why?
Used it quite a lot on my first Ruby file actually. After beating the Elite 4 for the first time on it my team for a very long time was Blaziken/Kyogre/Groudon/Rayquaza/Jirachi/Salamence. Other than that I haven't really used one in-game since then except for briefly during the Delta Episode in ORAS.
Competitively speaking, I haven't used the mega much since it got banned from Ubers fairly quickly on Showdown and I'm not into the AG meta at all. And Rayquaza is banned in rated Battle Spot so that just leaves unrated Battle Spot for my use of it really.....which I only tend to ever do when I'm sort of screwing around with an all Uber-legends team.
The base form though has gotten some use on Showdown though. This gen it was mostly as a Surf Rayquaza, which was a thing (dunno if it still is) in early ORAS Ubers since it made a decent surprise check to Primal Groudon since Air Lock negates Primal Groudon's Water immunity via Desolate Land. Haven't used it much in a while though.
What do you think of Rayquaza's design? Its mega evolution design?
The base form is kind of a scaleless Asian dragon, but the mega form looks pretty cool.
Do you think its mega is alittle op?
Well.....yeah. Rayquaza was an already powerful Pokemon, with dual base 150 attacking stats and the movepool to make use of it, making it slightly unpredictable or a good wallbreaker, and a decent Speed stat for Ubers (base 95, which made it able to just outspeed the crapload of base 90s in Ubers). It also has access to priority in Extreme Speed and good boosting moves like Dragon Dance and Swords Dance. All that was holding back really was its relative frailty, lack of a good Flying STAB, and its Stealth Rock weakness.
But then they gave it a Mega Evolution. Its already impressive attacking stats got boosted even further, to be on par with that of Deoxys-Attack, a slight bulk increase, and more importantly, +20 base Speed, giving it a speed tier higher than the new Speed benchmark of OU (base 110), which is a higher speed meta than Ubers. The real kickers though were the new ability and the lack of needing a mega stone to go mega. Delta Stream eliminates its Stealth Rock weakness, makes it resistant to Electric, and makes the 4x Ice weakness more manageable. All with no drawbacks. And even Primal Groudon/Kyogre's Desolate Land/Primordial Sea can't overpower Delta Stream. The requirement of holding a mega stone in order to mega evolve was probably put in place as a sort of way to balance out the benefits of mega evolution; the Pokemon is already getting +100 to its base stats and possibly other changes, why should it get an item to make it even stronger? But then they kind of ignored that with Mega Ray. Now your super powerful dragon can make itself even more threatening with your item of choice. And it finally got the powerful Flying STAB it wanted in
Dragon Ascent.
And all that combined kinda makes Mega Rayquaza a little ridic. Fairies? Mega Ray don't care about Fairies. Except for Xerneas, but Xern is bonkers in its own way.
But at least the fact that Game Freak is willing to make a Pokemon as powerful as Mega Rayquaza or the Mega Mewtwos gives me hope that perhaps one day we'll see the Tao Dragon in all its might and it'll be playable too. Before I thought that there was a limit to how strong Game Freak was willing to make a Pokemon. Think of how strong the Zekrom, Reshiram, and Kyurem are individually. Think of how strong Black/White Kyurem, incomplete versions of the Tao Dragon, are. Back in Gen V I though that the Tao Dragon would've been much too strong for GF to consider making available to the player to use. But they've given us Mega Rayquaza, and Complete/Perfect/100% form Zygarde has the potenital to be immensely powerful too, so the Tao Dragon is no longer out of the question.
Its body has meteroids in it?
It does sound a little weird at first, but it does make sense. Pokemon for whatever reason has a (strong) connection to both outer space and rocks. Stones seem to routinely hold power for some reason. Evolution stones and mega stones, for example. Meteoroids are just flying space rocks really, so it's not too out there (for Pokemon anyway) for meteroids to contain enough power in them to act as a catalyst for Rayquaza's Mega Evolution.
/rant