Monster Hunter G Cheats - Wii

Unlock Offline Colors
MonoDevil (White Monoblos) - Kill a Silver Crown Sized Monoblos.
Rioheart (Pink Rathian) - Kill a Silver Crown Sized Rathian.
RioSoul (Blue Rathalos) - Kill a Silver Crown Sized Rathalos.

Unlock Trial Mode
Basarios' Trials - Complete "Basarios: Unseen Paril"
Kut Ku's Trials - Complete "Jungle Menace"
Monoblos' Trials - Complete "Horn of the Monoblos"
Cephadrome's Trials - Complete "The Land Shark"
Gravios' Trials - Complete "Terror of the Gravios!"
Gypceros' Trials - Complete "Slay The Gypceros!"
Khezu's Trials - Complete "The Shadow In The Cave"
Plesioth's Trials - Complete "Water Wyvern in the Desert"
Rathalos' Trials - Complete "Attack Of The Rathalos!"
Rathian's Trials - Complete either "Queen Of The Desert" or "Slay The Rathian!"

Unlock Offline Elder Quests
Furufuru - Buy a piece of Rangosta armor.
Diablos - Buy a piece of Monoblos armor.
Gravimos - Buy a piece of Galeos armor.
Deliver a firestone - Unlock and complete Gravimos, Diablos and Furufuru quests.
Lao Shan Long - Complete all offline quests including the alternate colored monsters unlocked by defeating a silver sized monsters (Monoblos, Rioleus, Rioleia).
Pink Rioleia and Blue Rioleus pair - Complete the firestone quest.