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Fossil Fighters Champions for the DS, and maybe Fossil Fighters Infinity Gear for the 3DS. Infinity Gear is made by a different team than the first two so I can't vouch for its quality.
Gameplay-wise, battles are like 3v3 rotation battles but with added mechanics. Dinosaurs that are in the back row support your active dino by giving it stat buffs (sometimes debuffs) so rotation and placement actually matter beyond the whole type matchup business.
You get new dinosaurs by digging out their fossils from dig sites spread out all over the place, which works like unearthing treasure in the Sinnoh Underground. Then you take the fossil to a machine to revive it. All dinos have a few different fossil pieces and collecting pieces of the same dino gives them permanent stat buffs and sometimes access to extra moves.
