OK, so beating Cerberus wasn't so hard to beat, once I figured out how to do it.
Just gotta keep float spells on everybody as much as possible and use dispel magic on Cerberus whenever it puts its Triple spell on itself. From there, it's just a matter of pounding away on it with weapons and Diablos. It's still a tough fight, because there were a couple times Cerberus got to use its Triple spell effectively and did some serious damage as a result.
With Cerberus taken care of, it's up to the top floor and Headmaster Martine's former office, no occupied by none other than our old buddy Seifer and his new mistress Sorceress Edea. He confirms that yes, he knows about our collective past at Edea's orphanage. Of course, he still thinks he's the fucking shit and brags about how he's better than the lowly monsters infesting the Garden. He also tries to taunt the other party members, in this case by bringing up his former “romance” with Rinoa and suggesting he wanted to know Selphie better.
From there, he says we're going to fight about all this because he's going to protect the Sorceress. He's a better fighter now than he was in Deling City, but there really wasn't anywhere to go but up from there. It's still a markedly easier fight than the one we just had with Cerberus.
When we hand Seifer his ass this time, Edea generates a magical hole in the floor and jumps through to the room below. Squall says he thinks the auditorium is the room below, so that's where we're going next.
Something to keep in mind here is that after this little fight, Seifer is still laid out on the floor, face down and barely conscious after we kicked his ass. From what I understand, that'll be an interesting little tidbit when we actually get down to the auditorium to go after Edea, as Seifer tells us we can't beat her, implying that he'll be where he is for awhile.
For now, though, it's time to call it a night, as it's getting late and I've got a busy few days ahead of me. So, until next time, stay safe, have fun, keep gaming, and DFTBA!