So far, he hasn't. Check Bulbapedia for anything in Pokemon that changes frequently.
Currently, Ash does no have any dragon types. The writers feel that it can make Ash more powerful than they would like him to be portrayed at this time.
No, it is exclusive to Pokemon White. Where you would catch Rufflet in White, you catch Vullaby in Black.
In Pokemon black you catch RESHIRAM and TORNADUS In Pokemon white you catch ZEKROM and THUNDERUS Sources : myself
you cant catch rayquaza in Pokemon black
You cannot catch a Rhydon in Black and White. You have to catch a Rhyhorn and level it up to level 42. Rhyhorn is only available in Pokemon White in White Forest.
In White Forest you but in Black you have to trade from White.
Unfortunately you cannot obtain Reshiram (Dragon/Fire) in Pokemon White, rather you can obtain Zekrom (Dragon/Electric). In my opinion, Reshiram is better, so i got Pokemon Black.
No, it is exclusive to Pokemon White. Where you would catch Rufflet in White, you catch Vullaby in Black.
In Pokemon black you catch RESHIRAM and TORNADUS In Pokemon white you catch ZEKROM and THUNDERUS Sources : myself
You can't catch it in Black, but you can catch it in White. In the White Forest.
go to dragon spiral tower, and catch a druddigon
You can not catch Braviary. You have to catch Rufflet in Pokemon White and evolve it.
It is exclusive to Pokemon White, you can't catch it in Pokemon Black. You would need to trade with someone who has white.
you cant catch rayquaza in Pokemon black
You cannot catch Thundurus in Pokemon Black, he is exclusive to Pokemon White.
You can't catch it in Pokemon Black. You'll need to trade for it from Pokemon White.
In black you can catch Reshiram and tornados. In white you can catch Zekrom and thunderos.
you have to get in Pokemon white