Tab completion and aliases need not be mutually exclusive. For instance, in zsh you can use:

    alias gs='git status'
    compdef _git gs=git-status

FYI: I also mapped g without parameters to `git status -sb` but g with parameters will simply execute everything as normal

    g () {
      if [ $# -eq 0 ]
      then
        git status -sb
      else
        git $*
      fi
    }
    compdef g=git