Given the existing list's difficulty, would, say, Yeldema (easiest WW dragon) go in Warmup or Disciple?

What's the toughest soloable dragon in WW (in theory if not in fact)?

More random ideas...
Black Dire
Cazel
Corrupted Seafury (warmup or too easy?)
Tangrin
Yeldema, Entariz, Ayillish, etc., etc.
-more Velious crap-