Here are 2 pairs of sleep-bottoms, a pants & a shorts. They both have an almost-identical pattern. The only difference seems to be the angle of the cut of the fabric & the darkness of the blue background. Sonic logos repeat on the blue/blue background. There are 2 poses for Sonic & 1 pose for Knuckles which repeats all over the fabric as well. Notice the classic S&K art is MIXED with modern logos. This is probably an error, official stuff shouldn't do that.
Each has an elastic waist-band & the shorts have a red cord to tie in the front. Both of these were found at Kohl's stores in the boys area...however teens could probably fit into the larger sizes. These were available in about 2012 or 2011.