I did it was a 35-37 party of Luceus, Terry, Bianca and Jessica, gave Terry and MC the accessory that bypasses blocking and killed the 2 adds ASAP, then just baited out Psaro's attacks (he charges for a second before starting his combo), dodge around behind him and get a few hits in. Gets a bit harder when he goes to phase 2, whenever he did his dark attack I'd just run away, then go back to baiting his charge attacks.
Don't beat yourself up he is a DLC boss.
I was around level 40 with my main and 3 levels below with most my others, my main and my other heaviest hitter held dogged callers and the rest had stimulating goggles to start at 30% tension.
*He is obsessed with the controlled character and will waste time running toward who ever you switch to as long as he's not already attacking
**learn his moves so you can switch when your buddies are far away and he's headed towards you then switch out and build tension by beating up on the rose guardians until you see his icon coming towards you again you then switch to someone else when you've built some distance and repeat
Rose guardians strongest attack is that teleport strike that can cut your hp in half rather easily. Always be weary of it on your controlled character, your A.I. allies dodge it on their own most of the time
**When he does his gravity move you can get a few free hits before rolling out of the way
My goal was to make sure all my people had their tension bar full as soon as possible and once they did had them hit hik with tension one by one, being careful to hit him with the coup de grace before he starts throwing his 2nd stage one hit death blows because he will kill the others who are also whomping on him before they can blast theirs off.
**Coup De grace will stun him good and he takes his time getting back into the battle so bringing all heavy hitters will make the end come sooner
I hit him with all 4 coup de grace and he died
after so many other strategies, including trying to kill the rose guardians failed me.
As soon as I had that strategy down in my head, he was as good as gone.
Thanks for the tips guys!