You need the HM5 Flash.
first you need to get cut then go to cerulean cut the tree then pass rocktunnel go to lavender town, Then you go to the pokemon tower and fight your way to the top!
you have to get pass or rainbow pass
you just fight them
I think you have to get it in an Nintendo event
you have to get a rainbow pass
You get the national dex and the rainbow pass after getting the ruby!
rainbow pass
you have to have the rainbow pass. you take the ferry
To get Moltres in Leafgreen, get a tri-pass or rainbow-pass and go to one island. Then go to Mount Ember, and get to the end. There you will find Moltres.
Pokemon event only
I think you can only pass Pokemon from Emerald to Diamond/Pearl
you have to get a Nintendo event at washing dc go to Pokemon .com for more answers.