Go to the indicated coordinates to find the corresponding costume for purchase for Koins.
Press Up(2), Triangle at a character variation selection screen to play as that base character.
Fight through the Premier Living Tower until you reach your sixth opponent. Win that fight with a "Flawless Victory" with either a Fatality or Brutality at the end. You can restart the match if they take a hit and not be disqualified. After the match, you will start the "Secret Battle" against Reptile.
While playing Living Towers you will eventually unlock the Juggle modifier. Use it to lower gravity, which will make juggles easier and allows an easy 10 hit combo when you corner an opponent.
Set up your Kombat Kard with FXP buffed items. Start a two player Kustom Kombat match played solo with the Brutal Kombat modifier selected. Win the match with a brutality, then repeat the process as many times are required.
Traditional "Test your Might" towers will increment your progress. Go through all characters, and skip those you already have done a tower with.
Use the following trick to farm experience, Faction experience, and Koins, as well as practice Brutalities. This requires two controllers. Go to "Two Player", and "Kustom Kombat". Select the desired fighters then choose "Modifiers". Two of them need to be "Brutality Kombat" and "Dizzy Fatality Kombat". The other two should be Mods that do not throw random things (such as rockets, falling heads, etc.), for example, "Infinite Time" and "Super Meter". Dizzy Fatality Kombat causes both players to randomly become dizzy, and the opponent can perform their fatality at that time to end the match. Brutality Kombat eliminates the requirements to perform Brutalities. Because of this, a Brutality can be performed at any time, ending the match resulting in instant finish, a flawless victory, and bonuses. You can adjust your Kombat Kard to add more bonuses for when you perform the Brutality. Repeat the process as many times as desired.