Here is where I did manual testing with UBB's

Here I did auto-battle testing

Guaranteed criticals were on during this test and Lasswell's only SP is 30% Attack/Recovery so not as high as it could be

The UBB order was Ensa (600% BB Attack, ailment damage 200%) -> Shura (300% spark damage, 300% Critical damage) -> Zellha (300% ailment damage, 300% Elemental weakness damage) -> Felice (guaranteed spark critical, also 600% BB Atk) -> Galtier (250% Defense -> Attack) -> then Lasswell

Lasswell's damage seems good, very good in certain circumstances. But, only in the training sim can this be achieved properly is what I've observed. His spheres were Golden Lion Regalia and Demonic Skull (not the best, I know, but I worked with what I had) I didn't have any Lasswell friends on hand so Shura was the next best thing.

From what I observed, auto-battle isn't what you want with Lasswell, manual BB/SBB/UBB is what you want to use for him.

Maximum defense was on the training dummies so that might have affected it.

But tell me what you think then :/