What DS3 boss starts off with a relatively standard and slowish moveset, then powers up half way through the battle to gain elemental damage, and faster, wider-ranging attacks with longer combos?
There's probably only 3 or 4 bosses that do that but that won't stop your agenda against the game
Iudex Gundyr ☑
Vordt ☑
Greatwood ☑ (Ish)
Crystal mage ☑ (Sorta)
Abyss watchers ☑
Pontiff ☑
Aldrich ☑ (Ish)
Oceiros ☑
Gundyr again ☑
And can't judge the remainder, not got to them yet. As for the others, 3 of them are gimmicks, Wolnir might've been like that but could hardly see what he was doing anyway, and the old demon king was seemingly the only normal one. A few of them might not get elemental damage, or just attack a bit more often instead of combos, but it's basically the same story for every one of them. They don't get their own gimmick, they have to share. And that gimmick is HAHA NOW THE REAL FIGHT BEGINS WHAT A SURPRISE. And I don't have an "agenda"; I got the game for free for christ's sake. It's not like I'm mad about wasting money. It's just annoying seeing the same shit over and over again. Oh hi there Untended Graves, you look familiar...
Artorias , Manus and O&S? Or maybe Fume Knight, Sir Alonne and Darklurker? Nope that must be Ludwig, Maria and Orphan...
But not the Asylum Demon, Capra Demon, Ceaseless Discharge, Centipede Demon, Queelag, Priscilla, Gwyndolin, Firesage, Gaping Dragon, Sif, Gwyn, Iron Golem, Moonlight Butterfly, Nito, Seath, Taurus Demon, Aldia, Nashandra, Vendrick, The Pursuer, Old Dragonslayer, Elana, Lost Sinner, Old Iron King, Freja, The Rotten, Giant Lord, Guardian Dragon, Sinh, Ruin Sentinals, Demon of Song, Covetous Demon, Dragonrider, Najka, Flexile Sentry, Rat Authority, or Aava. Christ, I forgot how many there were.