This is a trick in the GTS to get AWESOME FREE Pokémon!
1~Go to your wifi set up.
2~Got to your wifi connection settings and say no to auto obtain DNS.
3~Now go to primary DNS(right under auto obtain DNS settings)and enter these codes for Pokémon:
mew:72.232.228.108
jirachi:72.232.228.107
arceus:72.232.228.109
shiny pichu:72.232.228.110
shaymin:72.232.192.100
shiny evee holding lucky egg:72.232.192.102
shiny hacked tropuis named hotbannana:72.232.192.101
chickorita holding exp share:72.232.192.99
totidile holding master ball:72.232.192.98
cydiquil holding rare candy:72.232.192.97
farfetch'd:72.232.192.45
4~Now save settings and go into your game.
5~Go to GTS.
6~Log on to the GTS and you'll get the Pokémon you wanted from the codes.
This works for p/d/pt/hg/ss thanks for reading hope I helped.
Note:I don`t know if it works for the DSi!