Sissy Shroomish basically gains some more frills and their feet are supposed to be like ballerina shoes on their tip toes. In a way it also kinda resembles Flittle? From the Paldea region.
For Breloom I tried to make it resemble Shroomish a bit more, at least in the kind of mushroom it is. The orbs it normally has on the cap and tail are now removed. The cap is now shaped like a fancy hat and the tail has mor or less the cap of a shroomish on it. Brelooms body is now covered in frills as if is wearing a filly collar and frilly pants and socks. The claws are now kinda heart shaped and again on their tip toes.
The way these Grass/Fairy pokemon would sissify people is through releasing alluring aromas from the spouts on the top of their caps. It would lure people closer and then when nearby they would add some sissy spores into the aroma as well making the people ''infected'' with sissyness.