how to use "to do" or "to be done"?

The tree is not going to decorate anything with accessories, but it itself is going to be decorated with the accessories, so the Second one "This tree is moved to be decorated with accessories" is correct. and IS or Was depends on what the speaker intends to convey, If He/she refers to past action then "Was "will be used.. I hope this explanation answers your query.

To do/ to move - infinitive in active voice to be done/ to be moved - infinitive in passive voice

The verb MOVE is transitive (They moved the tree.) and intransitive as well (The tree moved in the whirlwind.)

To the question 'which is correct?' ...to decorate with accessories..., or to be decorated with accessories. It is the latter, because someone is to decorate the tree; and the tree is to be decorated by someone.