Go to the tileset editor and open the grasland tileset. Then go to map 16


Now you can select the tiles you need from the right and paint it on the left (you should recreate the tiles you need for the mount).

Then you go the Tile Behaviors and select those tiles.
For the gras-thingie-ground you select this Tile Behavior:

It allows Mario to jump trough from the bottom and stand on top.
For the other ones you just use 00 00 00 00 (which is nothing, so Mario can walk trough).

EDIT:
After that you need to add them in the objects.
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You should be done when you decompressed only those 2:

I did the same and it worked because the needed stuff is stored in one of those 2.

EDIT: The first one is actually decompressed all time IIRC.
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You are not supposed to do it like this
After you decompressed it, just open the WHOLE ROM in a HEX Editor and change it. After that you are done. You can just continue editing/playing/whatever.
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Now you shouldn't rush the final castle. Just take as much time as you need and make it an awesome castle.
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The file is so small that it can't contain the nodes for all Worlds, not even world 1.
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Value 1 is the speed. The number I inserted there is actually the same speed as if Mario would be at his max speed when running.
Value 3 is the acceleration.
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The settings that are supposed to be known aren't even VISISBLE in the current sprite data. We had to copy it from NSHB because the sprite data used shows an empty dropdown box for the settings. Those settings don't exist anymore.
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Dayum that looks so good I actually like both a lot but the gras looks a bit blurry
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Google Docs has way more possibilities than the wiki.
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As far as I know in RicBent's WMe you can see the animation path, not the actual path. That's a big difference.
 Freeze is currently working on making those paths visible. It's not yet complete tho.
Yellow paths are forward paths and
Orange paths are the matching backward paths.



Also, I would not recommend RicBent's Animation Path generator since it creates incredible big files. A file created with his generator, storing only one animation, is already 2 KB bigger than Nintendos File with all of the animations.

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35 04 50 05 is for blue shell only brick just in case you want to have it.
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Posting this here as well, as it might be useful for some people trying to get into Model hacking on the 3DS.

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