[quote=@VarionusNW]
The rarity rule for structure decks (http://yugioh.wikia.com/wiki/Structure_Deck click here to learn about it) will not be enforced so that custom card structure decks can function.
[/quote]

So yeah. If you want to build a structure deck you just need to make it structure-like. Rarity of the cards doesn't matter. It's how I run like a ton of rare cards. Ally of justice is a little ludicrous when it comes to that.