1. The purpose of the transfer
2. The specific type of entities involved
3. The financial condition of the entities (i.e. debt and asset levels)
4. The consideration for transfer, if any
Let's take a look at the purpose of the transfer. Why exactly are you thinking of transferring assets from one company you already own to another one you own? This is an important question to ask as this type of action can lead to significant legal and tax consequences if done improperly.
How to properly handle the transfer is somewhat dependent on the specific entities involved. Each entity is a separate legal entity and needs to be treated as such to avoid having the assets and liabilities of the entities from being treated as the same.
The financial condition of the entities is also an important factor to consider. If the company you would like to transfer assets out of is facing bankruptcy or dissolution, a transfer could be viewed as a way of hindering the collection claims process of the creditors.
Will the company receiving the assets be providing any sort of consideration (i.e. payment) for the new assets received? If you have other shareholders or members involved in the company then they will likely want to be compensated for any transfer.
As you can see, I just highlighted a few of the many factors that you need to consider when making this decision. As such, I highly recommend that you consult with a CPA and a tax lawyer given the potential tax and legal consequences for moving forward.