As many as you can.
You have to dig it up underground, like most of the other plates. Or, you can also find under the waterfall in the Pokemon league.
in Pokemon diamond ,pearl ,and platinum you find them underground other Pokemon games you are most likely to find them on the ground in small poke balls
go into the underground, that's were you will find any fossil Pokemon. except on diamond, you cannot get a shieldon or lileap. those are only found on pearl. then go to the oreburgh museum and give your fossils to the professor and he will revive them!
If by "stones for Pokemon" you mean Fossils you can find them at the Underground once you have the National Pokedex since most fossils are not of Pokemon that are included in the normal Pokedex: Kabuto, Anorith, Leelip, Omanite, Aerodactile.
Arceus
Well the legendary Pokemon is Dialga but most of the other Pokemon are the same.
Most game stores.
Dialga!!!
The best Pokemon on Pokemon diamond is obviously a Bidoof...Joke :)No this is entirley an opinion based question but the best aka most powerful,and most defensive is Diagla
Arceus the Alpha Omega God Pokemon
i would have to say Dark Rai
im sure it giratina