To unlock everything in the shadow fight 2 titans, you must first have to complete levels to earn money as a reward, claim daily rewards to earn extra, and also take part in the daily and weekly online events to get rare items and surprises.
When you collect enough amount of money you can unlock anything that you wish to unlock or use in the game. On the hand, as an alternative, you can download the modified version of the game since in it you will get everything unlocked at the start of the game without doing anything.