Baragon would be the hardest to consider. In DAM he was supposedly an ally, but he was an enemy in GMK. However he's Godzilla's ally in the comics so I'd have to say Baragon is Godzilla's ally. Varan and Manda are most likely allies to Godzilla.
In the movies, they are never enemies. But there's a deleted scene in Destroy All Monsters where Manda and Godzilla fight... while they're both under the Kilaaks' control.
and Baragon was his enemy in GMK.
Well they didn't fight with Godzilla but I think they would be allies.