Infernal Takumi, I was dreading it after finishing the Lunatic stage, but it was really fun.
What I used:
So like what Conq said, Aether tank is really useful.
I didn't break any crates and left Tiki up in the top left to hold off the left side, and it was a bit headache inducing until I noticed that the blue Cav couldn't move across the screen for some reason and then I saw the conveniently placed trenches in the middle. That made it easier. Drive Def on Elise helped keep her alive. Meanwhile I sent FCorrin off to the right to slowly make her way down.
Felicia played a big role in helping her do her job well. There was this one instance when Corrin barely couldn't kill the first Takumi (the one on the right) by 1 hp and so I switched her breath to a +atk refinement, but that caused another issue earlier in the battle where I kill the cleric too soon and couldn't also get Felicia's def/res debuff off on everyone as well. Poor cleric, being the sandbag for spreading both Corrin's offensive debuffs and Felicia's defensive debuffs to everyone around. So I had to switch Corrin's refinement to +def instead to help keep her alive and also the cleric alive for Felicia. That left me with the problem of not being able to kill Takumi, so I gave Felicia the Spur Atk seal to help with that.
I didn't have anything in mind for Felicia's C slot (no ploys, sob sob) so I stuck her with her default Breath of Life, and it surprisingly goes off more often that not. Kind of anti-synergistic with Corrin's Wrath, but that's easy to avoid accidentally healing her out of range.