Basically you need for the GE and BE
- A ticket, or something that replaces a ticket.
- A reservation
The reservation is the same regardlles of what ticket you have. So it does not matter if you picked the wrong pass during the reservation, as they all amount to the same here.
An Eurail Pass will indeed cover you here. But it may not be the best option. You could also look at getting a Saver Day Pass for the day you are travelling, or if you are spending more time in Switzerland, a Swiss Travel Pass or the Half Fare Card.
