I ripped some of this before, but it was oversized and crappy, also limited. I've now ripped pretty much ALL of the sprites that are not part of the actual picross gameplay; meaning everything that basically matters. These are Super Mario Picross ...
Updated with much more. A large set of the main things you need to make a Castle Bleck Level. Custom made by KPP, no credit needed. Do not claim. Also contains an inverted version so you can make white objects with black outlining, along with black objects ...
Backgrounds from the SNES shooting game, Yoshi's Safari. May be updated later with Boo Mansion and Bowser's Castle backgrounds. Also has a few extra sprites! Ripped by King Piranha Plant.
All the sprites you would want from Super Mario Picross -- there isn't really much more to rip than this. Despite what the sheet says, no credit is needed.