sa2 VS pokefirered

Definitely definitely look at doing your project as a decomp using pokefirered or The Complete Fire Red Upgrade.

Pokémon Ruby/Sapphire, Pokémon FireRed/LeafGreen and Pokémon Emerald.

The quickest way would be to edit the decompilation. All the graphics are stored there as separate files there allowing you to easily replace them.

The "Person ID" is what I was referring to in my previous reply. You should write the ID of a flag there. Then make sure the flag is cleared if you want the NPC to appear and make sure it's set if you want it to not appear. You can find a list of valid and unused flags here.

Or use the pokefirered source code decompilation project.

You will have to program those mechanics into the game. You can do that by using the pokefirered decompilation.

If you're just now trying to get into romhacking, the best thing to do is to check out the pokefirered decomp project here. I have the most up to date video tutorial series for the decomps, I use pokeemerald in my tutorials but a large part of everything is the same. We have access to the full decompiled source code, so it's really easy to make changes to whatever you want and the workflow is practically identical to what the actual Pokemon devs would have been doing, whereas binary hacking, the old outdated method, is its own entire thing.

Weird question but, how do games which are coded like pokemon work? https://github.com/pret/pokefirered/tree/master/src for example this disassembly in c. Seems like each component has its own file, like battle.c or trade.c etc. How do these components communicate with each other? How and where does the main gameloop run? I would be very glad to get more info and write something like this game on my own (each component in own file, not pokemon 2)) ), because I'm not good at game architecture and cant resolve this on my own. thx in advance