Obviously you need the ram guardian equipped. I got this whilst using the basic green guardian which only offers 3 psychic breakers to start with. If you have better colours you will be faster.
Psychic breakers are performed when the opponent is mid combo by pressing the same strength punch and kick at the same time - so weak punch and kick at the same time makes you perform a psychic breaker.
If you are going for the completion this should come naturally but to quicken the process just use your ram guardian more often. Losing health quickens the recharge of psychic breakers with this guardian. With a decent colour ram it won't take many matches to unlock. Tbh even with my shitty green ram it didn't take long - was managing 10 or so per match by delaying the match by staying alive/keeping the opponent alive.