if you have an AR for the gba
You cant, Only you can use a Game Shark.
First get a gameshark then look online for codes after that put the gameshark in the leafgreen game then type in codes. Also the codes can get you Pokemon and items instead of looking and looking you can get them easily. Most gamesharks are $15 to $20. Hope this helps ;)
Careful! This can destroy your game1
Sorry, NOPE.
No,but you can put codes your Ultimate Codes for Pokemon for gba
put male and female Pokemon to the day-care.
You can only put one Pokemon in that daycare.
defeat it in battle
Pokemon codes are the codes you put in a action repley to get money, Pokemon, HMs and TMs, shiny Pokemon and complete your pokedex
Yes put leafgreen in the GBA slot in your DS and put Diamond in the DS Slot play Diamond and choose migrate to leafgreen follow the instructions then choose six Pokemon to migrate after your done go to the pal park to capture the 6 Pokemon you chose.
no there isn't that is unless you were to hack your game and put it in there