Unreleased G1 ponies

[Deep Purple Crystal]

I agree about the 'Celestials' as they were called. Though I can image that their star... Thingies above their heads would be a pain to find in good condition.
The book you found is awesome, Mimic. It is not only hard to find, but features an obscure comic character, Lady Lessons! However, it's 'twin' book, Rainbow Riders Birthday Adventure, is really weird ( It is up on the possibly defunct  Heck Yeah  Pony Scans).
I wish they had made a Baby Truly, although I don't know why she was a unicorn there. Design oversight, or did they just need a unicorn for the set? Who knows?

[mimicsno1fan]

oh i didnt know there was a sister book! I shall get online and have a look now!

[Deep Purple Crystal]

Yes, there was. It is incredibly bizarre, and features a very smug Sea Breeze/ Surfing Days (UK name) illustration on one page of it.