Direct Assault!
Ballistic Rhino: I used Sideswiper - Sweep Dive for Kraad and Heavyweight - Absolute Strike for Dylan. Dashed to the back and attacked until I had around 20 AP, then used the Thunder Gem. Rhino will use Violent Purge (+60 AP to the party). Then I just kept attacking. Didn't the Thunder Gem at the beginning hit/break the armor?
Ooze: Pretty much the same thing. Maybe the problem is that you used Mithra against Rhino. Since experience is shared you might have missed a level because of that. Lower Gem damage, and also less ATK for Kraad.
Sack Mimics are immune to instant-breaking. I'd try using Lezard's Fire Storm (fire is the only element the Sack doesn't resist). Link 4 Blue Apples on him if necessary.
Ooze: Pretty much the same thing. Maybe the problem is that you used Mithra against Rhino. Since experience is shared you might have missed a level because of that. Lower Gem damage, and also less ATK for Kraad.
Sack Mimics are immune to instant-breaking. I'd try using Lezard's Fire Storm (fire is the only element the Sack doesn't resist). Link 4 Blue Apples on him if necessary.