Gender change and Mog Station items

[Halivel]

I just checked, you can transform female gear to male gear and vice versa with :

Wedding clothings
Swiming suits (all colors)
Lightning's set to Snow's set
Yukatas and Suikans
The Valentine thingy (the apron I think ?)

And that's about it. Unless I missed something in the PNJ's choices

These are all Seasonal rewards from previous years (excluding wedding clothes), yeah, you can transform them. There are also few other seasonal sets that should be changable. Mog-station exclusives (like Korean and Chinese styles) aren't, sadly.