I've been hired by two different 135s with an already existent type rating on the airframe in which I was hired.
On one of them, my type rating was less than a year old. I had to do a full recurrent under their training program, which consisted of a 135 check ride at the end.
On the other, since it had been more than 36 months (3 years) since my last training event, I had to do an entire initial type course, followed by a 135 checkride at the end.
The above are pretty common scenarios, but it all depends upon the 135 operator's training program, as mentioned upthread.
For example:
A friend of a friend's buddy just got laid off from Jet half-way through 550 school this past week.
Jet was "gracious" enough to let him finish the course and get his type (it was already paid for, so why not?).
Through networking, he got picked up by another of the "Big 3" management companies, and they're going to immediately send him to a 550 recurrent right after he finishes Indoc.
Even though the ink isn't even dry on his brand new type, he's bound by his new employer's training program.