Inserting new letters and symbols "?"

Hey the great wisdom of the PokeCommunity forums,

The hack I am creating is a TCG like Emerald hack, with Pokemon based on the EX series of the TCG, such as EX Delta Species (eg new typings based off the expansion.)

My problem is, how do I insert letters, symbols and characters that aren't in the base game, specifically the delta symbol, "?" (among others.)

It would be nice to differentiate between the Delta and normal types of the same Pokemon.

I believe the game has Japaneese characters still within the rom, you could probably replace the sprite of one of those.

You would edit one of the characters in the existing character set to your new one, preferably an unused Japanese character. It's basically just font editing, and any font editing tutorial will be able to help you. You may need to update your table file in your hex editor with the new character and its hex code, and will probably have to know the hex code for your new character for XSE.