Like its previous game, the player takes a short "personality test" to determine his starting deck and then can win additional cards by defeating opponents as well as new monster cards by defeating dungeon bosses.
Each player's deck consists of three monster cards and an additional fifty attack/defense/support cards. Monster cards start in play, have HP, and a type (either ground or air). Attack are always specific to one monster breed, defense cards can be specific to one monster breed, and support cards. To use these cards, a player usually has to pay an activation cost in the form of a resource called "guts".
Source: Wikipedia, "Monster Rancher Battle Card Game", available under the CC-BY-SA License.