I played a lot of PSO back in the dreamcast days and only saw 1 Al Rappy and no other rare creatures.
This morning I saw 2 Al Rappys on the Gallon's Plan Quest. Both drop HP Material to raise HPs by 2. It was a nice surprise and I recorded the videos if any one is interested.
part one (please note the rappys appear in part 2)
http://youtu.be/hyXschx9ARU
part two
http://youtu.be/xhLi_kirBwE
Also last night I was in the caves and saw a Nar Lilly.
Are the rare creature's set to appear a little more frequently on the Ultima Server?