On this distant star, each tribe or clan fights to ultimately reign supreme. For the longest time, the war just waged on, with no one group holding the advantage. However, this battle that no one thought would ever end was suddenly brought to an abrupt halt, as the "Worms", invaders from outer space, suddenly crashed on the planet.
To combat the invaders, the tribes and clans were forced to form a truce and unite together. The four tribes that were the most powerful forces on the continent form their own organization, "Ally of Justice". Bringing together each of their technologies and crafts, they began to develop anti-Worm weapons.
This archetype is rather unique among all others. Most archetypes tend to not focus exclusively upon destroying one particular category of opposing monsters. Indeed, against most Decks many of the cards in this Archetype will be useless. Fortunately, "DNA Transplant" can be used to set all opposing monsters to LIGHT to benefit from their effects while protecting it with "Imperial Custom".
Instead of relying on your opponent playing LIGHT monsters. Instead use cards like "Creature Swap" or "Mystic Box" to give control to your opponent a LIGHT monster you control instead. So you can give your opponent a Gold or Silver Gadget and then Summon another Gadget from your deck.
Unfortunately, the vast majority of your monsters have no other positive effects when facing a deck that isn't primarily LIGHT. Even with "DNA Transplant" most of your monsters will still struggle to overcome any monster with very high attack or multiple monsters at a time. Even when facing a LIGHT deck, it is very easy for your deck to get outpaced or overwhelmed without your having disruption.
Ally of Justice as a deck on it's own has never seen any real success on large scale success, however a handful of their monsters have seen competitive play in some formats that had large amounts of LIGHT monsters in the format. "Ally of Justice Cycle Reader" and "Ally of Justice Decisive Armor". Ally of Justice Cycle Reader has had major success against formats against "Lightsworn" and "Blue-Eyes" decks, as well as being a Tuner.
"Ally of Justice Catastor" however, had seen years of competitive and casual play as a fantastic Synchro option from mainly 2009 to 2013. Catastor could deal with many boss monsters for the time, as well as being extremely easy to summon as a generic Synchro Monster. Even as of now it is a fantastic option against many monsters in the game.