Pokemon 4th Gen: Is there a way to trade pokemon on emulator after GTS shutdown?

I am playing Pokemon Diamond on Desmume and have a few Pokemon in my team that can only be evolved through trading. For the guides I found online that teach how to do trading using a emulator, all of them involves simulating a wifi connection and connect to GTS. However, GTS has been shutdown for generation IV already. So this method is no longer working.

I heard that if I have 2 real NDS in a close range (e.g. in the same room), I can still trade Pokemon on generation IV by using friend code. Is this true? And how can I simulate that using emulator (not restricted to Desmume)?

From DeSmuMe FAQ:

Read more information about the current state of DeSmuME's Wi-Fi support. Right now, it's an experimental feature, which means it is unsupported.

If you are an end-user, then we strongly discourage the use of Wi-Fi. However, as an end-user, if you really want to use Wi-Fi that badly, then you are on your own. In that case, any posts on our forums about Wi-Fi being used by end-users for end-user applications (such as wanting to trade Pokemon) will be ignored. Also, any submissions to any of our SourceForge trackers under the same conditions will be immediately closed without further consideration. When we say that Wi-Fi is unsupported, we mean it.

Short answer: no, it's currently not possible, at least, not with DeSmuMe.

I googled around a little, and stumbled on this gbatemp forum thread. I cannot try it, but you might want to give melonDS a try, since it also mentions successful Pokemon Trade.

(I'm not entirely sure whether I'm allowed to link to those sites, do let me know if I'm not)