This is easiest done with Jin Kisaragi. First, make sure your settings are as follows:
Game Difficulty: Beginner
Number of Rounds (Arcade): 1
Time Limit (Arcade): 30 seconds
Jin Kisaragi is known for being a "cheap" character due to his projectile attacks and his infamous Ice Car.
His Ice Car can be used by inputting: Quarter-circle-backwards (QCB) + //. If done correctly, Jin will jump on a shard of ice and hit his opponent twice for massive damage. Due to the low difficulty setting, one can simply keep using the Ice Car move over and over again to kill the opponent, this is because they will hardly ever retaliate or block your attacks. I suggest using the version of the attack, this is because it deals the most damage and travels the furthest distance.
Jin Kisaragi's Ice Blade can be used by inputting Quarter-circle-forwards (QCF) + //. I suggest using the version of the attack, as it is the fastest version. If done correctly, Jin will launch an Ice Blade at his opponent, dealing moderate damage. This can be used over and over to attain a time-out victory on your opponent as well as dealing tons of damage.
If you have 25 heat or more, you can use the version for both the Ice Car/Ice Blade to use an empowered attack which will freeze your opponent for a short period of time. This costs 25 heat and deals more damage.
You will most likely obtain the "PERFECTS" achievement using this method.