DS Walkthorughs and some ingame cheats needed

I'm a frequent player of this games and currently playing some of their versions.
Can you please give me some walkthroughs and cheats.
Here are my games.

Pokemon White/Soulsilver/Platinum
The World Ends with you
Shin Meagami Tensei: Devil Survivor(Too Difficult for me)
Megaman Starforce 3: Black Ace/Red Joker

Thanks for those who will help.

In Devil Survivor, it's a good idea to level grind in Free Battles.

I would actually recommend checking out GameFAQs for walkthroughs and cheats.