When saving in any outdoor area, you'll be put into a sinnoh void.
Starting at (0;0) there's a giant barrier surrounding the entire sinnoh map. If one could theorethically get past it without collision affecting you, you could save (or walk) anywhere in sinnoh's overworld without the use of battle tower voids, and with graphics active.
Many have tried to get past without any luck. This is where map 35 comes into play.
Map ID 35 corresponds to byron's gym, which has some interesting properties.
Unlike most maps, it loads models dynamically based on you taking an elevator.
Whenever you enter an elevator, you move upwards/downwards, and every level has its own 3D model with corresponding collision.
There's generally no issue with this, as this property removes itself when warping out of the gym.
Here is one of those models, which Ganix provided.
And this is a blank version of map 35 without loaded models.
[size=12pt][font=georgia]Utilising this property out of bounds[/font][/size]
In the void however, we can simply walk into this map and back out of it, meaning this property never gets removed.
This results in the 3D models being loaded at their corresponding coordinates, in whatever void you are.
(this is also around 0;0, because that's where all indoor maps are stored).
Here is a video showing me in a sinnoh void, but with elevators at the coordinates of map 35's elevators.
[size=12pt][font=georgia] The 'Barrier breach'.[/font][/size]
This property has some strange side effects. It seems to also affect map's and areas outside of the coordinates where the models are loaded, but I do not know why yet. I'm assuming it's because other maps are also affected by the property now. This essentially corrupts collision and gives a semi-walk through walls effect.
You can now walk through the barrier surrounding sinnoh, and walk through most of sinnoh with this scrambled collision.
Here is a video which shows the process of going to map 35 and going to sinnoh afterwards.
Here are two routes you can utilise to get to sinnoh with barrier breach active:
REGULAR BARRIER BREACH
Save and Reset
North until overworld
RETIRE MENU+BARRIER BREACH
14 S (Pal Park)
63 E (Or 64 if you have already been)
178 N (or north untill pal park)
North untill overworld (go left if walls are blocking you)
Big thnx to aera, he wrote a route based on my coordinates I saved in, and went through map 35 somewhere along the way.
This route was heavily utilised to figure out what caused the corruptions. I also wrote a manipulation route for map 35,
as the ones showed here use a static address to load map 35.
Barrier breach has some big issues though.
Whenever you refresh your graphics on hardware, the game will crash. Save resetting doesn't remove the properties of byron's gym,
which means that saving in this state puts you in a permanent softlock. You'd think warping would fix it, but warping also refreshes graphics meaning it crashes before it can even fix the issues.
However, it's still an interesting way to traverse through sinnoh, as walls are completely layed out differently and height
is still taken into account. Sometimes you can't enter maps because of height differences, but surfing on a water tile at the edge seems to put you on the correct height to enter.
I am uncertain if other maps also have such a property, or if they would work the same.
However some maps with elevators do crash when refreshing graphics, so I might check those out later.