1. It is good for you to move and laugh now.

Question

2. It is good of you to move and laugh now.
3. You are good to move and laugh now.
[Are the sentences all grammatical?]

Answer 1

All are correctly phrased, but 2 doesn't mean what 1 and 3 do.

1 and 3 mean it's all right to move now (as if everyone had been told to sit absolutely still for a while).

2 means the speaker appreciates the other person's actions of moving and laughing, almost as if in relief.