i was trying to trade my zigzagoon from ruby for a ditto from emerald. when I tried it said I couldnt trade ditto yet. any reason why? and when can i?
You need the National Dex in Pokémon Emerald in order to trade with Pokémon Ruby. You do not need the National Dex in Pokémon Ruby. You will get the National Dex in "Emerald" after defeating the Elite 4.