@[member='ferofax']
You are close. I'm going to bust your first and third fact.
Below is a GBA SP; it has a EXT.1 link port on the right and a EXT.2 Charger port on the left (mine actually, sorry for the crappy pix i'm rushing b4 work)
Below is a GBAphat; which has only the EXT.1 link port (again a pick of my gba).
Below is a DSphat; which has only the EXT.2 charger port (also my ds);
Fact #1: GBASP's link port and charge port is one and the same.
WRONG!! The GBA SP's link port and charger port are not one in the same
Fact #2: GBASPs connect just fine with GBAphats.
TRUTH!! The GBAphat and the GBA SP both have a EXT.1 port to link up with.
Fact #3: GBASP's charger works with DSphats (the plug fits).
WRONG!! The dsPHAT (while it is not labeled) only has an EXT.2 port, a huge mistake on Nintendo's part that makes me cry to this day.
Okay here is how it works; listen to my example. Recently I had a hard time booting GCN games on my wii off of anything besides a disk. I wanted to do it off something USB preferably a HDD but ended up being able to do it of an SD card. The reason this is dificult... when you go into gamecube mode... the wii as it is, is basically gamecube 2.0 so when you entre gamecube mode the wii thinks it is a gamecube and ignores all hardware the gamecube didn't have, so it's suddenly not looking to USB ports and SD card slots like the wii does.
The DS phat is basically GBA 2.0, when you boot into GBA mode it thinks the system is a GBA (yes I know there are work arounds to boot DS games off a GBA flash card but so too can my wii boot gcn games off an SD card, those are exceptions ignore them in this context. I'm just clairfying [spelling?] so no one disproves me, you can correcty my bad english spelling thought if you wan't some fun, give me credit though I'm on a membrain keyboard, my mechanical is on my other computer, anyway not important I'm rambeling)
Having stated the DS phat is the GBA 2.0, I'm saying that when you boot a GBA game the DS thinks it's a GBA and ignores all hardware the GBA did not have. This includes the DS's wireless card, the GBA phat or SP never had this. They had an adapter that was link cable to wireless which works differently to an internal dirrect wireless connection speck/specfication/standard (not sure of the correct word here). The rare and elucidate gba wireless link adapter was a work around to add hardware nintendo origionally left out.
So since the DS Phat in GBA mode can't see the DS's wifi card you can't use it, on top of that gba games were not written to utilise a wifi card like the DS has. They were written to use a link cable EXT.1 slot and are tricked into using a wireless adapter.
It is the biggest shame ever that nintendo left out the GBA EXT.1 link cable off the DS. If we had this we could trade DS phat to GBA or GBA SP and visa versa.
Instead the DS only has a EXT.2 port, which is the same as the EXT.2 charger port on the GBA SP, I know this because I have them and use their chargers interchangeably.
The problem with running an emulator on the DS Phat is, a few (I feel like this thought belongs somewhere else in my post but oh well, I'll type it here). I have an ez-flash iv, and run roms on it. They are able to use all of the GBA's hardware like the games are programed to, I can trade pokemon via link cable ect... it's easy because the ez-flash is just like a multi-boot game and less of a GBA emulator. It tricks the gba into thinking it's running the actualy game and works like the actualy game with anything else you patch in there like a reset hot key combo.
When running an emulator, the emulator is like a container, and you have to code the emulator to have a channel to talk on/through so the game can comunicate through the emulator to the hard ware. The ez-flash iv is not running a GBA emulator it just runs the roms natively and there is no emulator to talk thourgh so all your hardware works (except hardware YOU DONT HAVE like the wario ware twisted tip/tilt sensor or wifi adapter. I can run Fire Red on my ez-flash iv and the wireless EXT.1 adapter does work because the game is able to look for that hard ware and find it) This is one reason emulation normally takes +10x the power of the origional thing... because you have to emulate it... meaning you have to run the emulator and then then game inside of that emulator aka container (which is what an emulator is, a contianier... it's emulating the GBA hard ware on something else. Idk how to better say that without being redundant)
First off (there are the few problems I speak of) the emulator is not programmed to see the EXT.1 port because that feature was never needed the DS Phat has no EXT.1 port. So if they added the code it would be a waste of time, it would look and find no EXT.1 port. Secondly you can't program the game to use the DS's wifi card. IT would be extremely dificult, require editing the rom file (yes I know what rom stands for and you can edit a rom file but not the rom chips on the actual games) and you would still have to add a layer to the emulator to comunicate that from the game to the hardware, if this does work it only would on the DS because that is what we are trying to do... get a gba game to talk to the DS wifi card but I doubt my theory would work even if you could edit the rom because it's using hardware that was not origionally available on the GBA and to the GBA games.
The easiest solution which wont happen, the best flash card; super card DSTWO by superTeam (I think that's their name) has a working gba emulator called NDS-GBA which does everything but full screen GBA on the DSi XL. They update for stability occasionally. Adding this feature; a lay to the emulator that tricks the GBA game into thinking the DS's wifi card is the GBA's Wifi adapter, would work and would be amazing... (I think all you have to do is add something to the emulator to tell the ROM the emulator has a EXT.1 port, take that data and send that to the DS's hardware. I don't know how the ds's wifi card is different to the GBA wireless adapter but you might be able to send out a signal and recieve it. Problem could be: you want send the GBA signal from the DS wifi card and the DS might not be able to output the same signal the GBA wireless adapter does. You might be able to get a DS to wifi trade to another DS) but they won't get around to doing it. The vast complexity of this coupled with the limited use, just trading pokemon, with the added layer of maybe you'll only be able to DS to DS trade and not DS to GBA trade will be a huge impass to any design/development/programming team's motivation.
Push them to go openSource if they have not already so other people can do what they wont! If they do do it for us, I'll cook and eat my toque!!! If your south of my border that is a hat.
So to recap
The GBA phat has only a EXT.1 Link Port
The GBA SP has both a EXT.1 Link Port and a EXT.2 Charger port
The DS Phat has only a EXT.2 Charger port
Even if you could modify a link cable to fit into the DS's EXT.2 charger port... nothing would happen, that port is power only.
The EXT.1 port is data only (it might have small minimal voltage/wattage to send the signa)
BUT Long story stort EXT.1 is a data port and EXT.2 is a power port, and I'll say it again.
The GBA phat has only a EXT.1 Link Port
The GBA SP has both a EXT.1 Link Port and a EXT.2 Charger port
The DS Phat has only a EXT.2 Charger port
Sorry If I seem angry; I am not angry, just trying to be very clear about this so I am not misunderstood in my explination. I also don't mean to "shut you down" by busting your myths, I'm just trying to clear up misconseptions made by a lot of people.
And also sorry the photos are not in the same orientation and blury. GBA SP is shot right side up from the back, GBA was shot at a slant, idk what angle I did there. DS phat is upside down and backwords. I tried to get it so you can see the port and the text on the port but all I have within reach is a samsung galaxy player.
Hope this sets the record straight.
So @LeomelsonBato You cannot trade from the DS phat to the GBA SP or GBA (YET... until we push the superCard team to add that trick to the emulator to make the DS's wifi card look like the GBA wifi adapter to the GBA games, but only really pokemon used this)
ALSO ***Disclaimer*** I might have said trade my entre post, I meant link >_< I play so much pokemon the only thing I use the EXT.1 port/link port for is trading, so in my mind they are one in the same. I do know that you link to trade, just like you use the interent to use the WorldWideWeb and DeepNet and Drak Web

I understand the difference my eglish knowledge just does not show it. Parle francais a moi et je connais tres bien!