Help with Fire Red multiplayer

Sorry, I'm new to the community and I speak another language, so if anything is wrong, my sincere apologies.

I'm developing a hackrom and I'm still a beginner, but I already know a lot. But, working on my hackrom I'm in doubt what will hinder the multiplayer battle and the trade center, So I came here to ask them what changes cause bugs in this multiplayer function in pokemon fire red hackroms To avoid future problems. At the moment I just changed the pokemons and their types and for now everything is normal.

Some main questions about how multiplayer works:
• Do tilesets work?
• Change title screen works?
• Does adding new moves works?

I look forward to receiving an answer, and thank you very much for your attention.

Yes, adding / change tileset and move can disturb multiplayer, if it link with other rom that didnt have that tileset and new move.
Changing title screen didnt effect multiplayer