Have you ever used Dragonair competitively or during your epic journey?
I've used it yes... Only until it evolved into a Dragonite though.
How is Dragonair different from other Dragon types?
Well...Mostly because of its design I guess. But it's not really unique in terms of dragon design either. Rayquaza shares a similar design, although not, I think, based on the same dragon.
What were your thoughts when you came across it?
Eh. I've never actually been the biggest fan of this dragon evolution line. I think they're actually quite plain, and there are many better dragon types to fit their type.
What are your thoughts on it's overall design and pokédex description?
Its overall design as I mentioned above is plain. It's cool, but not really unique enough for it to stand out in my books, and it now gets overshadowed by Pokémon with more impressive designs like Noivern, Salamence and Hydreigon for example. I guess it's down to opinion, but I myself don't feel like it's the height of dragon types. Especially considering the fact it isn't even fully evolved.
Any artwork you found interesting on the internet about it?
Go type in Dragonair fanart into Google Images No because I don't really take much interest in the Pokémon and never really bothered to research it.
What's the best move it has?
Erm... Draco Meteor? Dragon Rush? It's not really competitive or often left long enough to warrant a finished or developed moveset put to it.
Exclusively, do you think Dragonair should get a Mega Evolution?
What? An unevolved Pokémon getting a Mega? Don't be silly! No way. Even if all fully-evolved Pokémon had Megas, I wouldn't want any Pokémon that have evolutions to get a Mega. Kinda besides the point then, and every Pokémon turns into a super powerhouse and the game becomes boring. No, I think Megas should be limited to the few we have no and possibly a couple more.
Dragonair is really quite underwhelming, and eh, I am a little disappointed in the spotlight landing on it, since I don't have much to say about it. It's just not my type of Dragon.