I used a code called
"Complete battle subway" (thinking it would unlock that secret tower place)
but it made it so I can't get trophies.(I even beat the subway legit after using code)
Could someone please post a code to have all of the room trophies?
(or at least a code that allows me to get trophies)
I did a quick Google Search for a Battle Subway reset code or a code to get all trophies, but no results.
I'd suggest that you continue looking for a while, then you could trade all of your Pokémon to another cart to restart your game.
(That would be if you have access to another game cart/another DS.)