Can a cockatiel and green cheeked amazon parrot get along?
I would place them in seperate cages in close proximity and see how they communicate. If they try to get at each other through the bars aggressively, then they’re no good together. But if they try to get to each other curiously then give them some supervised time together outside the cages. Don’t let either invade the cage of the other as they might end up snapping at each other and the Amazon can very easily kill the cockatiel without even intending to.