If you want to use
pip3 with your Anaconda Python 3 installation, you can copy
[Python 3]/Scripts/ to
pip3-script.py in the same folder. These will then show up in your PATH, so running
pip3 install [x] will now work, and running
pip install [x] will still work for your Python 2 installation.
It seems like you can do a similar thing with
conda, if you are forced to install it for Spyder. Rename
conda-env.exe, etc. and add
[Python 2 Miniconda]/Scripts to your path.
(Thanks to Neil D. for the tip!)