This is what the Buffy wiki says about Adam: "He was part human, part demon, and part robot, and was to be the perfect organism, with the adaptability and intelligence of humans, and the strength and emotional detachment of demons."

I will defer to the general will of the players on that one.

But he was also supernatural in origin, which Riley and Principal Quark were not.

This answers the question definitively. Adam was not human.

Snyder is most certainly a foe. His presence hindered optimal functioning of the Scoobies. He relished in punishing Buffy and made it his mission to do so as often as possible.

I think Principal Snyder is a foe. He clearly acted in opposition to Buffy throughout his time on the show. Whether or not he was actually evil is irrelevant to his status as a "foe."

I'm not sold on Riley... I would need to hear some sort of defense to accept that.

I think Adam should be considered supernatural since he was comprised of demon (which you specified would be considered supernatural). Doyle, for example, was part human and part demon as well, but it's the part demon that classifies him as supernatural.

I agree. Adam is a wrong answer.

I'm willing to accept Principal Snyder, but have yet to hear a good defense for Riley (other than that he was a foe to my ability to stay awake).

Also, can someone refresh my memory, does The Master appear in any episode of Angel? In a flashback, perhaps?

The Master appears in s2 e7 of Angel. Multiple flashbacks. I watched this episode just last week.

Excellent, thanks!

Are we considering Oz as a good character turned evil? I always saw it as he can't control himself, not actively evil. Thoughts?

And is there a time Xander turned evil of his own accord (i.e. not possessed by a demon or anything like that)?

I think Oz is a no. Your question asked to name a character that switched allegiances. Oz was simply a werewolf, even when we was not in wolf form, but never wavered from his allegiance to the scoobies.

I think Xander is a yes. He obviously switched allegiances in "The Pack." He remained Xander at all times, with all his memories and thoughts yet became clearly evil. The fact that he was possessed, I think, is irrelevant to the question. The argument can be made the Angelus was 'possessed' with a soul that caused him to switch allegiances... So I don't see why possession disqualifies the answer as legitimate.
Xander can also be argued to have switched allegiances in "Halloween" where he became a soldier. He was briefly seen shooting at people before Willow convinces him to help her.
Xander becomes a vampire in "The Wish." It can be argued that since the events of this episode were corrected in the end, the Xander that became a vampire is a different person altogether and is thus not who is referred to by the answer of "Xander." That, I suppose, is a judgement call.
Even with the discounting of "Halloween" and "The Wish," I don't see any arguments against his foray to the side of evil in "The Pack."

Putting aside whether Oz can be considered evil, did he ever really turn? His condition existed pretty much right from the beginning.

Okay, Oz will be wrong and Xander will be correct.

As for Riley, I'm guessing someone chose him because at one point the Scoobies are at odds with the Initiative, of which Riley is a member, but he was always pretty pro-Scooby, so I'm going to say he's a wrong answer. Also I fucking hate Riley.

If Riley is going to be a wrong answer, I'm interested in seeing how my answer gets scored.

I'm also a bit interested in how we're pre-scoring certain things. Does that mean the arguing during the reveals won't be happening?

Alright, this is all scored out. When do we want to start?

You can argue during the proceedings if you want.

I say start now

I want to, but I'd also like people to get advance warning.

Well, his allegiances did shift when he was in wolf form. I mean, he had no allegiances then. Of course, whenever he was conscious of self, his allegiances didn't waver.

Xander had his sense of self modified in The Pack, I guess.

Screw 'em for having lives!

What percentage of people are generally present for the scoring of these games?

Is a lack of allegiance a switch in allegiance?

25 to 50% maybe?

Being present isn't in any real sense necessary to play, but it is probably the most enjoyable part of the game. Sadly, I'm in a management conference most of the next two days so I'll probably be very minimally involved (reading the thread after is also great though).

Yeah, it would be nice to have 10+ people around for the actual playing of the game.

The game will be 11 AM PST Wednesday.

I like tomorrow at 3 PST. I will at least be out of work and can use my phone while at dinner. That's just me though.

I made an executive decision for Wednesday, sorry. Works better for me.