Fashems is a toyline produced by Basic Fun. They seem to be a spin-off of the Basic Fun brand, Mash'Ems, with a focus on "squishy fashion fun!" The toys are indeed squishy-- they are liquid-filled effigies of various liscenced characters. Basic fun had a liscence to make My Little Pony characters into Fashems, but the lineup now focuses on other franchises. Their outsides are made of a rubbery, sticky material, strong enough to withstand abuse by children using them for their intended purpose (mashing). They are sold in capsules, so you don't know which character you'll be getting until you buy and open the package. These Trixies were bought at a thrift store, and are fuzzy from their many years.
Though these Trixies are dirty, they are among the best-surviving Fashems ponies that I've found at the thrift store. Frequently, they are missing wings or horns, have their paint rubbing off, or are just disgusting somehow.
For some reason, any acknowledgement of the existence of the My Little Pony Fashems has been wiped from the Basic Fun website. There were as many as 13 waves of My Little Pony Fashems, as well as store-exclusive non-wave releases. It is shocking how little official information about these toys exists aside from listings on shop websites (the majority of listings describe them as Mash'Ems). MLP Merch has the best information about the toys, and says that Series 1 released in 2013, with the available characters including the G4 show's "Mane six." Strangely enough, there are two different versions of Twilight Sparkle, one as a unicorn and one as an alicorn, but the most startling difference is in the size of their eyes.
The aforementioned Trixies belong to the MLP Fashems series 4, which released in 2016. Their big, fat, heads are certainly squishable (mashable, even), but their proclivity for attaching particles to themselves puts me off from ever touching them.