Dunkin Boomer released three well-known sets of stickers, which are documented on Bulbapedia here and here.
However, there was also a fourth set that came with Boomer bubble gum. It was released in 2000 and featured smaller stickers of 150 of the original 151 Gen 1 Pokémon—Mew was the only one missing. Note: The set contains less than 150 stickers, because on some stickers more than one Pokémon is featured.
This set was released in three different versions. I’ve taken the liberty of using @Julius19 's photo (source) to illustrate this, as the logo, trademark placement, and Pokémon names vary between versions. @Julius19 also provided additional information that there is a Russian version too, which is different in size and stance (see below).
I was able to purchase a complete set of the European version (which includes the German, French, and English names), and I’m happy to share it here with you. There’s currently no documentation of this set on E4, even though many species collectors have already added the items to their collections (e.g. @Julius19, @joponnes), and the stickers are relatively easy to find online (at least for some of the 3 different versions).
So, here are some close-ups for the details as well as the complete set of the fourth Dunkin Boomer release from 2000, for reference.
Hope this is helpful. 
Details
Complete set
Best,
orannge
