Mortal Kombat 11 Ultimate

Unlocking skins:

Successfully complete a character tutorial (go to the "Learn" menu, scroll
down to the bottom, and complete the series of tutorials) to unlock a skin
for the character used. This can be done for every character in the game.
Go to the Tower Of Time, and check the left-corner to find Character
Towers. Spend 25,000 koins to unlock these towers. Character Towers are
tower challenges tied to specific characters. You will earn gear for your
preferred character —- and you can get two extra skins if you complete them.
They are very difficult -- so it is recommended to wait until you have
leveled up before attempting these challenges. The rest of the skins can be
unlocked randomly as rewards for completing Tower Of Time or Klassic Tower
challenges. These rolls are completely random. If you want better chances,
visit the Krypt. At the Krypt, open chests that cost between 10,000 to
15,000 koins. These chests usually contain a skin for a random character.
Chests that cost between 12,000+ or 14,000+ almost always contain a skin
inside. Note: If you have opened all the chests on the island, you can
reset the rewards by finding the blue/white orb in the main Courtyard near
the entrance and use a special key to reset all the chests in the area.
There are two of these reset icons -- one is underground, and one is above
ground.

Team Battle mode:

At the main menu, select "Konquer" then "Towers Of Time". Successfully
complete the four tutorial towers to unlock the main towers. These change
every few days. One of them is usually a boss tower. You can tell because
it only has one opponent in it. Select the boss tower, and it will display
the "Group Battle" screen. Select "Search For Players" or "Invite Players".
Once the match begins, you will unlock the "Teamwork" achievement.

Mercy finisher:

Mercy is a special move that revives a dying opponent and gives them a bit
of health back. It can only be used in the last round of the match. When
the game says "Finish Him/Her," stand at mid-distance and quickly press
LT + Down, LT + Down, LT + Down (Xbox controller). To make it easier, just
spam LT + Down in quick succession. Additionally, by performing a Mercy
finisher, you will get two hearts instead of one.

Easy towers and rewards:

AI Fighters can be used as substitutes for almost every Tower Of Time
challenge. To use them, simply toggle on the "AI Fighter" option after
selecting a character, but before entering a battle. Using an AI Fighter
will earn you the exact same rewards as a standard fighter. All you
need to do is press continue between fights. For most battles using
AI Fighters, put most points in the "Combo" and "Reversal" stats. To
change AI Fighter settings, go to "Kustomize" and select a character.
Then, choose any "Kustom Loadout" and go to the AI Fighter tab. All
loadouts can be customized with AI Fighter settings —- you do not need
to create a new loadout. The best AI Fighters are Noob Saibot against
anyone, and Skarlet against fast rushing characters and powerful zoning.
Some bosses and hard battles cannot be completed with just the Combo
and Reversal stats. If your AI Fighter is losing, try switching tactics.
Select a "zoner", or a long-range character that is good at using
projectiles and other abilities. Skarlet is a powerful zoner —- equip
projectile skills to her loadout, and boost the "Zoning" and "Runaway"
stats to 30. Additionally, hearts are one of the rarest currencies in
the game. To get hearts, you need to kill opponents with a fatality or
brutality. You only get one per fight, so it can take awhile to get 250
—- which is required to open a Shao Kahn chest. To easily grind hearts,
enter the Klassic Endless Tower and use an AI Fighter. They will
continuously fight, using finishers, and climb the ladder until they
are defeated. You will get lots of hearts using this method -- without
having to do much of anything.