You can't because the Rainbow Pass is a Key Item which can't be traded without a hack or glitch.
With the Rainbow Pass.
The rainbow pass is a key item in Pokemon FireRed version. To trigger the events to get it, you first need to own 60 different Pokemon.
There is no such thing as a "rainbow pass" or there is some diffrent name for it.
beat the elite 4
You must beat the seven gym leaders, the elite four, and your rival. Then you have to capture 60 Pokemon to get your Rainbow pass the will allow you to travel to Island 7 in Pokemon FireRed.
You need the Rainbow Pass
Defeat the rockets and follow the cavve at the right side of the base of Mt. Ember. The ruby is at the ned. Give it to Cellio to receive the Rainbow pass.
AnswerBeat the elite four.Go to Mt. Ember at one island then in mt. Go to b5f then get the ruby.Talk to celio and u will get the rainbow pass.
After beating the league go island 1 and go to ceilio. Talk to him and he'll give you the rainbow pass. it lets you go to the sevii islands.
Just defeat him lol.
Find the Ruby inside Mt ember and then give it to Celio.
It is not possible to obtain the rainbow pass in Pokémon Emerald. It is only available in Pokémon FireRed and LeafGreen.