Is it possible to use unityscript and boo together( in the same project) in unity 3d? We are trying to choose the platform and the engine to develop a game as a group and some coders are good in python and some others in js. So I will suggest unity as the engine if it is possible to combine these languages and work as a whole.
You can use all three of them in the same project. Even in the same object. In fact many of the example projects you can find on unity3d page use a mixture of JS and C#.
So technically nothing prevents you from using different languages within same project or even objects, however you should still consider to have one default language, because if you have several different languages, it will become harder for a C# developer to change code made in Boo (Python-like) if necessary and would always require him to ask the original script writer to make the changes.