This set of figures is called the Sonic Gashapon set. It's from Japan, and features 13 little 3D hard plastic figures inside display cubes. Each one came in an identical blue box, likely from a machine that vends them. You likely had to trade to gather them all. Aside from the main Sonic X cast, there were 2 "Secret Figures" to try and get.
As you can see here, all the figures are 3D, fully painted and detailed. They're not particularly to scale with eachother (Cheese is huge) but they're quite nice.
Wierd fact:
Do you notice something about the poses? They're EXACTLY the same as the newer Figures/Emeralds and some of the Mega Bot Toy Island larger action figure line! Why? It seems like a very strange coincidence...especially because these guys were made first.
There are the 2 secret figures. They're identical repaints of Sonic (of course) one in silver, the other gold. On the box there is even an outline of the "Mystery Figure" to let you know that it's a Sonic variant. The gold one, however, is rare-er than the silver, and it was likely released (?) later on into the set.
The boxes and lids all have little 'feet' so they'll stack and not topple, however the lids are easy to crack, and don't always snap onto the bases very well.
In all, this is a great set, well worth collecting, with quality.
All photos of the figures are by SonicGear, except the gold one, which is by Alex Z. You MAY be able to buy some of these figures at VideoGameFigure.com in 2009 winter.
Photo by Alex Z