>>536814169
Use Hold Breath first turn
From there Kris should just defend to build up TP, Susie spamming Rude Buster, and Ralsei should be attacking each turn. Ralsei maybe will hit for 30-ish damage but it contributes a lot (really). Was able to get Roaring Knight in his final attack sequence right at the end of his 2nd stage of attacks. Only issue I have with him is the knife attacks, but all of them can be avoided by moving left or right, the horizontal ones just involve up or down (move only when they turn crimson red)
Knife hallway can be tricky with the first set (eh) but the 2nd one is just a circular loop. Basically just replay him with this method and you can get him in the final sequence easily. Took me about 2 hours but was able to get the method down.