^Have you not like seen even one trailer yet? She was the first retro character to show up in the bloody announcement trailer back during Sony's not-TGS pre-TGS TGS, not to mention all the other trailers and screenshots she's popped up in.
Psaro is stupidly popular in Japan, I'm not really surprised he's in. I'm more surprised that he wasn't announced already, actually.
(Of IV's villains, I actually preferred Estark. That battle felt much more grand-epic-final-battle-y to me. Also, better boss theme).
I liked Psaro better when he was a seven formed/phased boss fight instead of DWs Odo Nobunaga. Unlike the DQV's remakes' Waifu retcon changing a loaded choice into a legitimate one, DQIV's remakes' Chapter VI retcon was largely stupid and useless and I've never liked it. Estark was definitely good, but he's also just kind of a monster in the ground plotwise (thankfully, the series has been reusing him ever since).