Well, Dissidia NT's Story Mode goes in a really weird direction as it goes on. The story fractures into 4 separate paths early on, and when you reach near the end of each respective path, you need to fight one of Final Fantasy's summons (or in the case of Lightning's path, 4 of them) in a 3-on-1 duel.
And oh boy...are these fights
NOTHING like the rest of the game. Dissidia NT as a whole is a wacky, cartoony, button-mashy battle royale where 6 character run around hitting each other until they can REALLY hit each other. But these Summon Boss fights? Oh no...they're not Battle Royales at all. You see, Team Ninja made this game, and Team Ninja decided that what the story mode really needed are boss fights with
heavy pattern recognition, multiple phases, a totally different damage mechanic, & the bosses able to essentially one-hit kill you on a whim.
Yes, what's essentially a light-hearted Smash-style affair suddenly turns into Dark Souls in these encounters. What. The. ****? Each Summon presents their own delightful little problems, but easily the worst of these I've encountered was Ramuh.
The dude can hit anywhere on the field on a whim, and in his second phase he can easily kill you in seconds when he winds up Judgement Bolt or his big full-stage slam move.
I've managed to take down 5 of the Summons, and Ramuh was easily the worst. Ifrit & Odin look intimidating, but if you pick the available spellcaster you can hit them from mid-range without too much problem. Alexander was tricky, but once you get his patterns down he's not too hard.
Unfortunately, the remaining 3 have to be taken down with melee characters, and I can't imagine a worse way to play these battles. I only took down Bahamut because Noctis' Warp ability lets him essentially hold at mid-range & bamph in when there's an opening & then out again. I have to take down Shiva with Leviathan with pure melee characters, though. That's going to be...fun. -_-
Edit: Shiva & Leviathan down. Turns out that Shiva is really weak to Cloud's aerial attacks, and even with her 2nd phase leading to another Shiva joining the fight it wasn't too bad. Leviathan was more annoying, but thankfully at this point I had my AI characters leveled-up pretty decently so they were able to keep him distracted long enough for me to do some decent damage.
That just leaves the Final Boss of Story Mode: Shinryu.