Originally Posted by Fat Vladimir
Pray you haven't fought everyone in there yet, because there's only one wandering NPC, and he's directly below Landorus (a youngster with Yanma&Ledyba&Ninjask). As soon as you fight him, he stops moving around, but if you fought him and left the area... give up on shiny Landorus lol.
I haven't gotten to the point where you can encounter Landorus yet, so I don't know exactly how the encounter works, but as long as you are using frame 1 IVRNG spreads, you should have no problem at all getting a shiny Landorus.
1) Stand in front of Landorus or whatever it is you do and save.
2) Hit your seed, and immediately upon entering the game button-mash X to get into the game menu ASAP.
3) Cancel out of the menu and button-mash A to start the Landorus encounter. Don't use a Synchronizer for this encounter.
4) Figure out the initial PIDRNG frame from the nature. This will be slightly different than usual because of the NPCs, but at least this way you've adjusted for them. If necessary, repeat steps 2-3, each time saving\making Chatot calls once in order to advance the PIDRNG frame one.
5) Once you have your initial PIDRNG frame, go for the catch. Get your Synchronizer out, and make all the Chatot calls you need to advance the PIDRNG frame to the point where you get your shiny.
Of course, this only works when you have a frame 1 IVRNG spread (frame 8 in the case of eggs) but it works for all areas where NPCs are the only thing messing with your PIDRNG frame. Also only works if you're using Chatot calls, because saving results in you leaving the menu.