They were definitely trying to be super bosses which the game desperately needed, but a layer or two of additional strategy would have really been nice.

Maybe with shiva you might need to hit her with a fire attack before you could apply debuffs or do damage to her.

Or valefor being immune to non ranged melee attacks as it flies, I dunno just something other than a bigger health bar. Could have been cool.

Penance has a little more to him, having to deal with the 2 arms as they regen to ensure you don't get wiped so easily, but he was still just immune to everything and had a big bar.

FFX has something like 44 status effects and super bosses were immune to basically all of them, give me some reason to use these abilities like Triple Foul or Doom (think Auron had an overdrive that could apply break debuffs even to super bosses, but I think that was it).

It felt like the Devs overcompensating for making the actual final boss the easiest one in the series.