Classic battle is the traditional arcade mode most gamers are used to from Mortal Kombat and other fighters.
To find Classic Battle, simply go to Single Player - Battles, and then choose "Classic Battle" from the list.
There are a total of 24 characters as of this guide being written (12 heroes, 12 villains), so you must complete a Classic Battle with all 24 characters. Upon completing each battle, you will get a short cinematic about what happens to that character you played with, and you will also get some nice unlocks from each battle as well.
- To make this as easy as possible, you CAN play each classic battle on "Very Easy." Doing so will make each fight, literally, VERY EASY. In every battle I've completed on Very Easy, I never even got down to my second health bar.
- I also wanted to comment about experience. For each fight in classic battle, you gain experience. This is very helpful while working towards:
Experience is based on the time you have left, your health, the number of object interactions you complete, level transitions, if you use your supermove, and some other factors. HOWEVER, experience is not based on difficulty AT ALL. I assumed there may be a difficulty multiplier for the higher difficulties, however, I found none. In fact, I was able to score significantly more experience on Very Easy because I was able to execute more interactions and transitions than on higher difficulties. So not only is Very Easy the easiest way to win each battle, it will also help you level up.
- Since you will be playing with EVERY character on a variety of the stages, this is also a great time to work towards other achievements. You should be able to put a significant dent, if not complete, all of these achievements as well:
While there are other arguably easier ways to complete each of these achievements I've listed (see the excellent guides attached to each), since you have to beat battle mode with EVERY character anyways, there's no reason to not attempt to complete them during battle mode instead of practice or versus.
- Final tip: Use this time playing with each character to improve your combos with each one, and determine who you like using the most. It will come in handy for the multiplayer achievements!
*UPDATE* 4/21/15: Due to reports from multiple users, it appears that when working towards this achievement you should use ONLY the classic character skins. Using certain skins causes the game to not recognize your completion with that character. So, it is best to just use the standard skin for every character while working towards this achievement.
If there's anything wrong with my solution, please comment!
Good luck, and happy hunting!