These Ruling(s) have not been confirmed as applicable to the TCG.[Notes 1]
In place of declaring a FULL card name, a precise description of a card's stats, appearance, and/or effects, is considered acceptable so long as both players are in clear agreement over which card is being described.
In the case of a card like "Luster Dragon", since the original printing of "Luster Dragon #2" did not have the #2 by its card name, you should ask the player for additional information. If they say "The Level 6 one" is then enough information provided so that both players know which card it is.
During the resolution of this card, "your opponent cannot check cards in your Graveyard" is also applied, and your opponent cannot check cards.
If the bottom monster of your Graveyard cannot be Special Summoned, the effect which Special Summons the monster is not applied.
These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
Remember that you cannot shuffle your Graveyard or change the order of cards in your Graveyard at any time.
If you would Special Summon "Tyrant Dragon" from the Graveyard using "Question", you must Tribute 1 Dragon and if you cannot you cannot Special Summon "Tyrant Dragon" and the effect of "Question" disappears.
↑Konami Judge Program Rulings are considered unverified, as their source(s) are not publicly viewable. They are not confirmed as applicable to the TCG until they have been officially published by Konami.
↑The latest print of "Necrovalley" has Problem-Solving Card Text which states that it negates the effects of cards that move cards in the Graveyard to other locations, regardless of whether or not they target. Despite this effect not targeting, this ruling is correct that it is negated by "Necrovalley".