If you transfer a piece of real estate from one trust to another, do you need to do a warranty deed?

You will certainly need some sort of deed to submit to the Recorder of Deeds or County Assessor's Office. Whether that needs to be a warrantee deed will depend on the circumstances. If the property is entirely owned by one trust and is being sold to another trust, a warrantee deed would probably be appropriate. However, if the land is jointly owned by both trusts or there is some other unique situation, a quit claim deed may be sufficient.