Checkers

You can enable different checkers in emacs for python. The default
checker is the pyflakes one, since it’s the fastest and doesn’t have
false positives.

I’ve built also support for other two checkers, to enable them you
have to disable the pyflakes checker and to enable the other one, for
example:

(setq flymake-enable-pyflakes nil) ;; Disables pyflakes support
(setq flymake-enable-pep8 t) ;; Here what you want to enable

The available checkers are:

flymake-enable-pyflakes
flymake-enable-pep8
flymake-enable-pylint

If you want to write support for your own customized checker you can
check the epy-python.el comments for instructions (search in the file for “Flymake”).