You can catch Ditto in the Pokemon Village.
Pokemon X and Y cannot trade with Diamond, Pearl and Platinum.
Ditto and Dewott, or two Dewott
*Mew is not catchable in Pokemon x and y, but you can get him online from wondertrades and such. Mewtwo however, is catchable and you can find him in the cave in pokemon village.
Lots of people have ditto safaris you just have to find the people that do. Also the more friends you have the easier to end up with one, so go out there and make more friends and you might get lucky enough to get one.
Parfum Palace. Find the owner's Furfrou and he will give you it.
Dive is no longer a TM or a HM in Pokemon X/Y. You'll have to have a Pokemon learn it naturally.
Yes You Can Get A Pikachu In Pokemon X and Y.
The Legendary Pokemon available in Pokemon X/Y are:Xerneas (X only)Yveltal (Y only)ArticunoZapdosMoltresMewtwoZygarde
You may be able to find someone to trade a Special Torch for Pokemon C or Y in a Pokemon Facebook group.
Pokemon X and Y are sold at MSRP of $39.99 (CAD)
The list attached gives an overview of where they are