The Title

This page explains a little about the translation of the title of the show.

六門天外モンコレナイト

六	Roku	Six
門	Mon	Gate
天外	Tengai	Heaven + Beyond
モン	Mon	Mon, short for monster
コレ	Kore	Colle, short for collection
ナイト	Naito	Knight

A most strict translation would have it read as

Six Gate(s) Beyond Heaven Mon Colle Knight(s)

Since Tengai can be used to denote sky-wide distances, such as horizon, distant lands, heavenly shores and skyline, the more conventional translation is

Six Gate(s) Faraway Mon Colle Knight(s)

And a liberal translation that aims to catch the meaning of the title

The Mon Colle Knights Of The Six Gates Beyond This World