Find all sinnoh Pokemon
you get all the cheats by completeing the game and getting all the coins wink wink dont tell andyone ;)
on the national pokedex it is #130 on sinnohdex its #24
You get it by completeing a mission.
trade with somebody
for completeing the pokedex, 100% yes
by completeing challenges
No, sorry
by completeing computer repair quests in ziranek
a cirtificate saying you completed the game
You beat the game by completing the browser, defeating Darkrai, befriending all partner Pokemon, completeing all the secret and extra missions, and completeing all the jobs that people ask you to do.
By answering all of the questions!
Yes you get 1 hundred.