Hmm... I know PGE (Pokemon Game Editor), I'm pretty sure that can edit trades, but only to the extent of nicknames, IVs, OT (Trader Name), Trainer ID, Item, the Pokemon itself and what is needed to trade for the Pokemon. (Edit, I believe you should look at
this guide, it displays under 'Message Scripts' a spoiler that has each symbol for text that is in the code of Fire Red, and should apply to Emerald, after all, Fire Red was built on Ruby and Sapphire, and Emerald was built on a mixture of both games.)
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I run Dedenne, and I don't regret it one bit!