you need to find fossils underground. if you have national pokedex you can find aerodectyl's old amber, lileep, kabuto and anorith's fossils. if you have not got the national dex, if your trainer id ends with a odd number, you get skull fossils (cranidos) and if it ends with a even number you get armour fossils (sheildon).
The underground
you can probably get it Underground.
Mining and digging Underground.
You can find stones Underground. You take the explorer kit and then go underground.
you can find it while mining underground.
He isn't in the underground, you don't have to find him.
this is the same as Pokemon platinum, they are in the underground, they do take a while to find.
Go underground and dig one up.
you can find a thunder stone by checking the UNDERGROUND
I have no clue
take 50 flags in the underground
They r dug up underground. They are hard to find