How do you getArmarldo o In Pokemon sapphire?

On Route 111, in the upper right-hand corner where the two fossils are.

Choose the Claw Fossil, and head to Rustboro City.

Then, head up to the Devon Building's 2nd floor, and talk to the scientist at the bottom.

He'll talk to you about a fossil ressurection machine he's making, but needs an actual fossil to use.

He'll notice you have one, and ask if you would like to resurrect it.

Say "Yes", then leave the building. Head to the next town, have an extra slot in your party ready, then return to the 2nd floor of the building.

Talk to the scientist, and he'll tell you the resurrection process worked. He will then hand you an Anorith, the 1st stage evolution of Armaldo, once it reaches Lvl. 40.