Requirements:
- I have rxTools emuNand 10.7 with sysNand 9.2; I think you need to have CFW ready.
- Downgraded 3DS Browser (If you don't have one, follow this tutorial to get the downgraded 3ds browser: https://www.reddit.com/r/3dshacks/comments/402cri/how_to_downgrade_3ds_browser_to_more_vulnerable/)
- Exchange Booth Available (If you don't have access to Exchange Booth, download Mii Plaza Games cia and then you will have the access to it. Don't ask me for the link; google it.)
- 9999 ARCode Tickets: 127FD9F6 0000270F (For O3DS USA Only; "It doesn't work for N3DS at all. You'll need to use either a gateway or NTR to use any codes for N3DS users.")

Steps:
1. You first need to have downgraded 3DS browser, or else, you will not be able to do this.
2. If you have downgraded 3DS browser or are ready, go to https://lunarcookies.github.io/cheat.html to generate QR Code.
* For O3DS USA, use the above code and put that code into the "input codes" to generate QR Code.)
3. After getting QR Code, press L+R and then scan the QR Code.
4. Launch the browser and then wait for it to close with error.
5. Profit.

* If it is not working, open Mii Plaza first!
* UPDATE: It seems like Mii Plaza resets after you close it and open it back up.
If that happens, repeat the step, or use this code for "permanent tickets."

O3DS USA:
99 Plaza Tickets
0176CF90 00000063
027FD9F6 00000063

Questions? Leave a reply; I will try to answer.

- - - - -

UPDATE: SOMEONE MADE MII PLAZA EDITOR.
THE PERSON IS AMAZING.
YOU CAN STILL USE THIS METHOD, BUT IT IS TIME REQUIRING.
GO CHECK THIS PERSON'S WORK OUT!

https://gbatemp.net/threads/streetpass-mii-plaza-puzzle-swap-save-editor.420765/​

 

[Nirmonculus]

I used the method for 99 plaza tickets with ntr and I got into the browser using the qr code and it failed to give me any error whatsoever...

Either use ntr or just downgrading your browser for qr codes. No need to get both.

 

[DarkRioru]

Either use ntr or just downgrading your browser for qr codes. No need to get both.

where can I get the ntr cheat for 9999 plaza tickets?

 

[Mc Nasty]

When I came FFE panel made the code for this panel..Time after I got directions for all panels, lack of interest not convert to some funcional code..BUT if someone wants to apply to Gateway or NTR them there I leave information (names of the panels are Americans in Spanish) Only Fills th address with FFFFFFFFFF
168454B2 FFEXPLORERS
1684546E MYL PAPER *
1684546E ACHAPPY HOME
168435E6 YO-KAY
168452D6 MHUNTER
16845292 SSB 3DS
1684524E NES REMIX
1684520A CAP TOAD
168451C6 SONIC BOOM
16845182 pikmin DIA DURO *
1684513E pikmin TESORO EMBOTELLADO *
168450FA pikmin JUGO DE MEDIA NOCHE *
168450B6 FANTASY LIFE
1684502E KIRBY FIGHTERS *
16844FEA MEGAMAN
16844F1E RUSTY DEAL BASEBALL*
16844EDA YOSHI NEW ISLAND
16844E96 SM3D WORLD
16844E52 KIRBY T DELUXE
16844E0E MONSTER HUNTER
16844DCA PKMN XY
16844D42 CHIBI ROBO
16844CFE MYL DREAM TEAM
16844CBA TLOZ SKYWARD
16844C76 NEW SMB U
16844C32 XENOBLADE
16844BEE DIVAS NINTENDO
16844BAA DILLON ROLLING
16844B66 LUIGIS MANSION
16844B22 ACNL
16844ADE KIRBY RETURN
16844A9A NSMB2
168449CE BRIAN AGE *
1684498A MARIO TENIS
16844902 FIRE EMBLEM
168448BE KID ICARUS
1684487A PILOTWINGS *
16844836 DK COUNTRY *
168447F2 RYTHM HEAVEN *
168447AE MK7
1684476A SM 3D LAND
16844726 STARFOX 64 *
168446E2 ZELDA OOT *
* This panels fil FFFFFF

 

[putti]

FOR THOSE OF YOU WHO ARE INTERESTED IN MII PLAZA HACKING, GO TO https://gbatemp.net/threads/streetpass-mii-plaza-puzzle-swap-save-editor.420765/

SHE/HE IS AMAZING.

 

[BerserkLeon]

For NTR/Gateshark the 9999 tickets code would be
1576cf90 0000270F
167fd9f6 0000270F

Not sure if you need to reverse the 270F to 0f27 or not. You do have to with NTR's Debugger. Either way you end up with a lot of tickets though.
I'll toss it in a cheat plg in a bit
This one just has the tickets code. I found like 5 other codes on fort42 but they didn't work as-is or with a +C offset which is what the one code suggested. I might look into it later... But this means they're probably dynamic addresses that need a pointer or something and I've no idea how to do that.