Trying to install this on OS X 10.11, Node 4.2.1, npm 3.3.9.
Here is the output:

 work_folder  》 npm install -g generator-gulp-angular
/usr/local/lib
├── generator-gulp-angular@1.0.0
└── UNMET PEER DEPENDENCY yo@>=1.0.0
npm WARN EPEERINVALID generator-gulp-angular@1.0.0 requires a peer of yo@>=1.0.0 but none was installed.

However...

 work_folder  》 npm list -g | grep yo
│ └─┬ yosay@1.0.5
└─┬ yo@1.4.8
  └─┬ yosay@1.0.5

As you can see, I do have yo installed at the proper version level, and there are no other unmet dependencies. I have also opened this issue with yo directly as this seems to also be occurring with other generators that depend on yo as a peer.