I'm looking to transfer a client from a colleagues CM account to my own, is this possible to move the account and keep all previous sent campaigns reports templates etc?
The best answer to that is "it depends". It is possibile in some cases but not all. We'll have to have a look at both accounts to determine whether it's possible in this case.
Get in touch with support, make it clear what the two accounts are, and we'll have a look at the specifics.