How do you get cheat codes on Moshi Monsters?

Answer 1

Cheating is not allowed on Moshi Monsters.

There are MoPod codes for items.

MoPod code for Monster Species are unique and can only be used once by one member. Item MoPod codes can be used once but are the same for all members.

And there are Seed/Plant Combinations which catch moshling.

But both the MoPod codes and the Seed Combinations are part of playing the game, not cheats.