CoroCoro Japanese Promo - Reprinted edition
Japanese Ivy Pikachu Reprinted CoroCoro Variant
linkdu83’s collection
Collection of ProChaos → very nice source for quality scans of the “sheets”
→ note: a few are missing in his collection post (as fare as I can tell)*
and here can you find covers and scans of the magazines (the year and month you can find here (its the first number))
Shining Mew (CoroCoro promo)
Wiki - CoroCoro
Unnumbered Promotional cards (TCG)
Top 35 CoroCoro promo cards!
Pocket Monsters in 1996
Asobikata vol 1 Promo (Pikachu and Jigglypuff) + Coro Coro (No Jumbos)
いいものだけでも … Page 1&2
If you find any good info on your own, please share 
Good luck, in anticipation of an interesting collection post on the futureCracker
*I think by now a found good photos of each card, sheet and magazine cover (except of the reprints mentioned by KEI), if you need some, pm me