Phantom Dust

First you need 10,000 credits to buy a 1-School Arsenal Case. You can earn this easily by playing the SP game normally or repeating missions on the Memory Box Terminal in the Visions HQ room at the start of the game.

Buy the Arsenal Case,

Multiplayer Mode>Xbox Live>Shop>Buy Arsenal Case. Then buy the case for 10,000 credits.

Setting up case,

Multiplayer Mode>Xbox Live>Lab>Edit Arsenal. Select the one skill case (Limit[1]). Open it and it will be full of Aura Particles. Select an Aura Particle and replace it with a Psycho skill. Psycho skills are the skills with a pyramid with an eye in it symbol.
If you are playing a real match you'll need to build proper arsenal, not just add one skill for boosting purposes.

If you need to buy a Psycho skill,

Multiplayer Mode>Xbox Live>Shop>Buy Skill. Attack tab, you are looking for the pyramid with an eye in it symbol. Buy Power for 50 credits (or any other Psycho skill).

Complete list of skills here - http://phantomdusted.com/pd_skills.htm

To win the achievement you have to select the single-school Psycho arsenal case when setting up either a Xbox Live match or a split screen match. The opponent can't just quit, you either have to beat him or he has to kill himself.

Load up a split screen match and make a 1 School Arsenal in the Lab with whatever school it is you're going for. Be it Faith, Nature etc. And then play on the Highway and with the second controller just walk off the map. Rinse and repeat with the other schools.