Battle Card (Mario & Luigi: Paper Jam)

Battle Cards are items introduced in Mario & Luigi: Paper Jam. They replace the Badges from previous games, and can be used in battle to power up the Mario bros, power down enemies or implement various other special effects and abilities. Unlike the badges in earlier games, multiple cards with the same effect can be used in a single battle, with the effects being multiplied based on the number of cards used (so a 25% extra EXP card and a 50% extra EXP card can be used together to get 75% more EXP than normal).

In this game, the initial set of cards are given to the Mario bros by the Paper Goomba they free from the Twinsy Tropics dungeon. After this, they can then be purchased from the card shop in any of the game's towns or unlocked by completing mini games and Lakitu Centre quests. Cards are set up in the Battle Cards menu, with up to ten cards being assigned to a set and the player being able to switch between three sets at any point in time.

Once at least one set of Battle Cards is set up, then up to three cards will be present in the deck in battle. Their effects can be used by spending Star Points, which are gained by pulling off normal, Bros and Trio Attacks in battle. Good ratings (like Great or Excellent) add up to three Star Points to the counter, lower ratings add between half a point and one point to the counter. Any cards used are then later replaced by later ones in the deck when the next turn comes around.

If the deck runs out of cards, then no new ones will be drawn until the remaining cards are used, at which point the deck is reshuffled and the cycle repeats anew.

Shiny Battle Cards
In addition to the normal cards you can buy in shops, there are also shiny Battle Cards that are dropped by Shiny Paper enemies found at random across the world. These are more powerful versions of the normal cards, which cost half the amount of Star Points to use in battle.

amiibo Cards
As well as standard battle cards, special amiibo Cards can also be used the same way. These are created by taking a special Level 1 or Level 2 amiibo Card and then scanning an amiibo into the game, which will create a special card whose design and effect relates to the amiibo character. Level 1 amiibo Cards and Level 2 amiibo Cards can either be purchased by a Toad inside any Card shop, or found after defeating certain enemies in battle.

Usage by Enemies
Battle Cards are also used by certain bosses in the game, with Larry and Ludwig using their own set in their boss battles in Twinsy Tropics and Neo Bowser Castle. They have their own Star Points (referred to as Dark Star Points in game) which can be gained by hurting the Mario bros in battle. Some of these effects including shrinking the party down, reducing their attack power or defence and hitting them for 180 damage.

Trivia

 * One of the amiibo Cards that can be created with a Bowser amiibo has a picture of Antasma on the front. This is because the card uses artwork from Mario & Luigi: Dream Team, where both characters are featured in some of the same pieces of artwork.