Unfortunately, some of the DL live rounds require a costume that you don’t have both category and type. It’s doable in rounds 1-3, but the 4th round can be pretty difficult without a good set up. Some people may have a different strategy, but this worked out for me.
My general approach in completing those kinds of DL live rounds is to wear a S-rank costume that satisfies category but not type. That way I have increase number of memories which will help tremendously especially with the triple bonus you get from memory appeals for satisfying category. Plus, having perfect combo bonus from the S-rank costume helps.
Also, having a good set up with accessories helps a lot too.
I would recommend obtaining the S-rank costumes from DL lives 1-6 since those are guarantee. Then, having 1 S-rank costume from main game plus having some luck from DL lives should get you a set of s-rank costumes you’ll need.
Surprisingly, I was able to Ex all DL lives at this point. I hope this helps.
If you’re still having difficulties, then we may need to dig deeper. Like, are you optimizing your accessories set up? Or, are you optimizing scoring strategies, etc.