We're playing in a bachelor party/golf outing tomorrow and we should have around 10 guys.

We were thinking of playing 2 man teams and playing 6 holes scramble, 6 holes alternate shot, and 6 holes best ball. Is there an official name to this game?

It's kind of like Ryder Cup format but with the scramble thrown in there.

What is this called?

I'm not sure there is an official name for this format. I've heard people refer to it as "Pinehurst". But, technically Pinehurst is something different.

I have heard of it referred to as Round Robin (Any combination of formats that changes every 6 holes)

But, Round Robin also referrs to the format where a foursome switches partners every 6 holes:

Drivers (Both drivers are on one team)
Carts (Each cart is a team)
Opposites (Driver of one cart and rider of other cart on a team)

All the course around me call it a "2 man 6-6-6 tournament".

I have heard it called "Triple Skills" also..