Yes, you can revive Pokemon from Fossils in Black 2, and yes, Sheildon can be revived from a Fossil.
Sheildon can be revived from a Armor Fossil, which can be found in the Ice Rock room in Twist Mountain from a Worker who gives out a random Fossil from older Generations each day (if you don't get an Armor Fossil from him, you'll have to wait a day for him to give you another one).
Once you have the Fossil, take it to the Nacrene City Museum and talk to the lady at the counter. She will take your Fossil and turn it into a level 20 Shieldon.
