Yes. Numerous pokemon are only available through trading, for rare pokemon or evolutionary purposes. Examples include Machamp, which requires that Machoke is traded to another game, and Mew, which must be traded to LeafGreen through an Emerald game that has the pokemon.
trade
You have to trade with firered or leafgreen to get the national pokedex.
trade it from ruby sapphire or emerald after getting the national pokedex.
you don't need a national pokedex to trade from ruby to leaf green. You have to get the gems the sapphire and the ruby in order to trade from leaf green to ruby. These are found in leaf green. (:
The best way to trade i guess wuld be to 'MIGRATE' from LeafGreen, in Pal Park to do this you need to beat the elite four and get the national pokedex
you dont
you must have the national pokedex at search for it in the trall grass and catch it or trade it from firered or leafgreen
the kanto pokedex YES national not sure but i think you have to trade from ruby or sapphire or something
By seeing or having all 150 pokemon if you want to complete national pokedex then you have to trade or migrate to your game(s)
This is an upgraded version of the pokedex you will get this after becoming pokmeon champion as long as you recorded 60 species of Pokemon in the pokedex.
You can either trade Quilava from Coliseum and evolve it, or complete the Hoenn pokedex in Emerald and receive Cyndaquil from Prof. Elm and trade it over and evolve it.
Unfortunantely, it's impossible to catch ANY Pokemon from the National PokeDex in Ruby and Sapphire. You have to trade with FireRed, LeafGreen, Emerald, Colosseum, or XD to get Pokemon from the National PokeDex. If you trade with the first three games, you'll actually get the National PokeDex in Ruby and Sapphire.