All chests are filled with various items including Gold, Gems, and Cards, and other items.

[Chest Types]
The are 6 main chest types - Normal, Silver, Gold, Rare, Unique, and Epic.
Each chest type can further be divided into different grades in order of ascending value - Shining, Huge, and Superb.

Other than the chest types mentioned above, there are additional special chests that can be acquired through gameplay.

[Match Star Chests]
Can be unlocked when enough "Match Stars" are accumulated from winning 1vs1 Matches.
Upto 2 Match Star Chests can be unlocked within 8 hours.

[Battle Star Chests]
Can be unlocked when enough "Battle Stars" are accumulated from Battle Royale Matches.
You can earn more Battle Stars depending on your standing in Battle Royale matches (1st - 3 Stars, 2nd - 2 Stars, 3rd - 1 Star).
There are 4 types of Battle Star Chests (Beginner, Light, Super, Royal) one for each stage.
Upto 1 Battle Star Chest of each type can be unlocked within 8 hours.