[Other] [Emerald] various questions: roaming, deoxys,...

[Haltmann]

I've got some questions about hacking Emerald that are making it hard for me to work on my hack.
If someone could answer them, that'd be greatly appreciated!

-How can I add roaming Pokémon to Emerald?
-How can I edit Deoxys-Speed's moves or prevent it from changing its form upon capture?
-How can I add one-time encounters for Pokémon like Mewtwo?
-How can I add more person sprites to the game (for instance, an NPC sprite that's found in FRLG but not in RSE)?

Thanks a lot!

 

[STikER]

-How can I add roaming Pokémon to Emerald?
-How can I edit Deoxys-Speed's moves or prevent it from changing its form upon capture?
-How can I add one-time encounters for Pokémon like Mewtwo?
-How can I add more person sprites to the game (for instance, an NPC sprite that's found in FRLG but not in RSE)?

Changing Deoxys Forme from Speed to Normal (sprites, icon and stats): https://www.pokecommunity.com/posts/9001424
Deoxys' moveset is easily editable through any Pokemon editor (for example, the one included in PGE), in-game it doesn't change depending on Forme.

One-time encounter is triggered by a script applied to the overworld sprite on a map with a command:

setwildbattle 0xAA 0xBB 0xCC

where AA is the index number of the Pokemon, BB is the level of the Pokemon and CC is the held item of the Pokemon, all in hex. Also there should be additional commands such as flag checks, hiding overworld sprite after defeating, catching or fleeing and so on.
And if you're new to the scripting I suggest you reading this scripting tutorial first: https://www.pokecommunity.com/threads/164276

About adding new overworld sprites... I tried to figure out how to do it, but really, I don't know if it's possible. Anyway, if I remember right, there are some unused OW in the game, also if trading won't be part of your game you can edit Red's and Leaf's sprite.

Can't say absolutely anything about roaming Pokemon, sorry. Hope I provided some help.