Like Kiva said, they are not rangers...they are masters. They called the spirit rangers when needed...they are allies. Apparently at the PR section at Wikipedia, in the list Rangers section, those 3 are listed...not sure why when they are mainly allies. No need to count them.
As for the Phantom Ranger.....not really necessary to count him. Most fans consider him as a allie more than a ranger while that he is designated as a ranger.
Don't really need to add Alex to the list....he was only a Red Ranger in Force from the Future part 1 and for episode 29 and 30...he gave the morpher back to Wes near the end of episode 30.
Minus the 3 spirit rangers, Phantom Ranger and Alex: Its 89 but if including Mike, Daggeron and Leanbown...that makes 92 in total