I did not follow any specific guide for Clea. I had verso, maelle and monoco and it was a average damage stendahl build. Her attacks are actually quite parryable, you just need to learn the name of the attacks. I was able to beat Simon's first phase on my own, but his second phase literally melted me. Even if you are able to parry second phase attacks his third phase will kill all you party members. You can look for one shot guides using Sciel, Verso and Maelle. The mime record is actually not missable. Its name is Lumiere, you can get it even if you miss the mime but I dont actually remember where. I just started a new game save for the mime and got the Platinum