Nate,
At about 0500z (2200 lcl) Phoenix Tower combines to Local South on 120.9 The controller will typically transmit on 118.7 simultaneously, but almost all aircraft will be on 120.9.
The TRACON is trickier. Since we moved into the new building, located at the base of the new tower, it is possible to combine to any position. What normally happens around 0500z is that positions are combined to one departure and one arrival sector.
The departure sector will have aircraft on both 126.8 and 119.2. This controller will also transmit on and monitor the following satellite frequencies: 120.7, 123.7 and 124.9. Another frequency, 127.45, is used to communicate with aircraft on the ground at SDL after SDL Tower closes at 0400z. The transmitter and receiver for 127.45 is located at SDL but is used by PHX TRACON.
The arrival controller will be transmitting on 128.65, 124.1, 126.6, and 120.4. The aircraft coming from ZAB will be on either 128.65 or 124.1. A good technique from a controller's point of view is to have ZAB issue the same frequency for all aircraft, but which frequency will vary from night to night. Between 0500-0530z this position can get interesting if it is combined. If the controller on 128.65/124.1 is instructing aircraft to contact 126.6 or 120.4 it means a Finals sector is still open.
Usually, shortly after 0600z, all TRACON positions are combined. It is most common to use a departure freq (126.8) for the majority of traffic although aircraft may call on any of the others listed. A controller will transmit on many freqs at once, if you don't hear the reply from aircraft then they are on one of the others I listed.
LH, P50