You can find them or buy them at a place.
Pp up
you can buy pp up from level 1 in the department store in veilstone. from the left of the Pokemon center there, go up on the raised path and turn left. it's the huge building on the end.
pp ups are things that put you're Pokemon's pp up
pp stands for power points. it's how many times a Pokemon can use a move. a pp up increaces that amount. for example, the move giga drain usually has 5 pp. if you use a pp up on that Pokemon's giga drain, it will be able to use that move 6 or 7 times. they are relatively hard to find, so use them well!
You can buy Protein, as well as Iron, Zinc, Carbos, PP Up, and all the other stat boosters, on the second floor of the Veilstone Department Store. They cost $9800 each, and never buy more than ten for each Pokemon.
it fully restores the pp of either all or one of your pokemons moves i forget
it restores the pp of all moves of one Pokemon by i think 5
Elixir restores the PP of a Pokemon's move. There are two types of Elixir: Elixir, and Max Elixir, which restores the PP of all of a Pokemon's moves.
all over the place
Right, You cannot get an pp max in Pokemon diamond or Pokemon pearl nor platinum!
Pp up
It brings 10 pp back to one move that your pokemon knows
Elixer and Max Elixer both refill pp, normal elixer recovers 5pp while max recovers the max pp. The item pp-up will increase any moves pp by 20% of its max pp.
25
20
Full Restore
none do