The World Monster Cup - Naga Returns

When Mum Mew asks about his plans, General Durahan says that he has already found a very strong monster who can deal with the gang. As they signed up for the World Monster Cup, the gang realized that they don't have a partner for Mocchi that is in IMA's designated list so they went around only to encounter Naga of the Big Bad Four! Naga says that he has changed and has trained hard to regain his fighting skills and would like to help them out. Everyone but Suezo trusts him. Naga displays unbelievable fighting abilities but can he be trusted? And what's with this very strong monster General Durahan found?