Remember that Ugobus was a First initiative that did cover the city, initially to undermine PCB and then to scupper the sale. What then happened was that First were losing their shirts once PCB had the backing of a major group and then had to back away, withdrawing much of the Ugobus network. PCB however then pursued the battle to Tavi and Torpoint etc.
First were hammered and the operation that was left was sold for a nominal £1 to Stagecoach if only to avoid the redundancy costs etc. Go Ahead and Stagecoach knew there was no way that they could have a war so quickly retreated to their territories.
I remember Ugobus. With it, they changed the whole numbering system of well established routes, which confused many locals. In Plymstock with the 5 and 6 (which is almost identical to PCB 5/5A), by the 5 now doing the Mount Gould loop and rerouting the 6 so it only went one way round the Holmwood Avenue loop as a terminus from the Staddiscombe end caused a lot of complaints at the time, with longer journey times. That opened the doors for PCB to register the 5 and 5A, copying the old 5&6, and apart from Oreston who stayed loyal, first lost a lot of custom on that route. PCB have also tried and failed on the Hooe corridor, which First and then stagecoach won the battle with the 2 (formerly the 7A many moons ago). If first left the 5 & 6 alone, I dare say the The Ride ops would still be operating it today and having the monopoly in Plymstock.
Plympton was always well covered by PCB, so first retreated. They lost Keyham to PCB, which they held for many years prior to Ugobus.
If their routes were more carefully planned out then they may have come out of the other side. When it was the Overground with coloured routes, such as the green, purple, orange, blue, red etc, it was easy to understand. Ugobus may have been great for some areas, but they forgot about their bread and butter by placing clapped out P and R reg darts on altered routes, with the odd vintage step dart and Olympian thrown in, and lost out.
After that, they retreated, slashed fares and became the bargain basement operation using old bangers, with the Purple Pound in Efford being a prime example, forgetting that many in that area are on passes anyway.