Bulbapedia - list of moves
By index number, Pound is the first, and therefore oldest, move.
I think that makes sense, since Mew is the original Pokemon and Pound is its first starting move, making Pound the original move (I guess?).
As for no-longer used moves, I don't think there are any. All moves are still available to the Pokemon that can learn them, via levelling, breeding, TM etc. etc.