hmm. Personally I know zero scripting ahaha. Funny right? I know what you're thinking, why is this guy making a hack then? Well I plan on learning obviously. Anyways yeah...I have no idea how to make either of those possible, however your second idea with the tree pokemon sounds interesting
I have two ideas on it, although they might not even work.
1. Place scripts in the beginning and end of the route. Once you step on them, they should randomly generate numbers (using the randomnumber command) and if it generates a number that you like, have it erase the flag of the person event who's overworld looks like shaking grass. Of course then you can't walk on it, you'd have to talk to it, but it's roughly the same.
2. The other one I don't even know if it's possible. Start off with the script and the random number thing, and if it's something, there's a change tile command to change the tile so you could change it to a tile with a shaking grass animation. There's also wild encounter data for trees which no-one uses, if you could find a way to link it to your shaking grass tile, you got yourself a working shaking grass.
I think I used Kyledove's black and white tiles for the trees and the grass, if that helps. And it's okay if our hacks look similar, it's the story that'll make ours very different. I think yours will be very distinctly different than mine's, especially since I'm starting to deviate from the normal plot.
Dude, so so I was looking at tiles for my remake and I was like oh let's use the HGSS grass. Then I looked at your thread and I was like crap. Lol dude our hacks are going to look kinda alike with Wesleyfg's tiles, HGSS grass, prolly other generic BW tiles. However I will try my best to make our two hacks different from each other