A very quick and undoubtedly overly cusory look at the Aircraft Location Reports shows that the only PBY equipped unit operating out of Guam on a consistant basis in 1945 was a sometimes 2, sometimes 3, PBY detachment from VPB-23.
You can find the location reports here
http://www.history.navy.mil/a-record...-ac/loc-ac.htm
VPB, VH, and VE squadrons can be found in the Pacific Fleet Air Wings section of each report.
The VPB-23 history can be found here
http://www.history.navy.mil/avh-vol2/chap4-2.pdf
The VH squadrons in the Marianas generally operated out of Saipan, VH-1, for example, out of Saipan also operated PBY-5s, but also operated PB2Y-3s and PBM-3Ds. VH-1 was later joined by VH-3 operating PBM-3Rs.
The VE squadrons were reorganized in early January 1945 into Fleet Air Evac Wing 1 and were stationed at various locations about the Pacific. VE-1 was based out of Ulithi with detachments at Saipan, Kaneohe, and San Diego. VE-2 showed up at Guam in early March, equipped with R4D-5 and -6s.
Rich