Continuing in the proud tradition of fossil Pokemon comesTirtouga and Carracosta, whose design seems to most closely resemble a sea turtle. Once you've received the fossil from the backpacker in theRelic Castle inside the Resort Desert, you can head over the museum in Nacrene City to revive it. Unfortunately, you have to choose between theCover Fossil (Tirtouga) and thePlume Fossil (Archen), so make sure you pick up the other Pokemon from a friend or the GTS.
In terms of battle,Carracosta is definitely geared toward the physical side, with excellent Physical Defense and Attack stats. If you're not afraid to go on the offensive, Shell Smash is an excellent way to boost Carracosta's already terrifying Attack stat while at the same time make up for its absolutely terrible Speed stat a little. You've got a lot of options for physical STAB attacks in both Water and Rock, so take your pick.