Trivia card

Trivia card ネタカード (Netakādo)
Japanese Wiki: 7478

A Trivia Card is a slang term for cards which are notable in the fandom for reasons other than being powerful in the competitive Metagame. It is a type of in-joke and can often make players laugh.

Features

The Following are often features of trivia cards;

Cards that are so weak that they are useless in actual gameplay. (Example: Aqua Master, Meteorage Lizard)
Cards whose power in the background story or Flavor Text do not match the actual card. (Example: Emperor Quazla, Supernova Black Hole Thanatos)
Extremely Overkill cards. (Example: Supernova Betelgeuse Final Cannon, All Over The World, Supreme True Dragon Soul)
Cards that were so powerful that they were known for creating a degenerate metagame that damages the game's playability. (Example: Bombazar, Dragon of Destiny, Aqua Patrol)
Cards that are obvious parodies of other franchises. (Example: Tatsurion, Yattar Wan, Adventuring Fox)
Cards with distinct illustration, card names, or flavor text. (Example: Dekodekko Dekorianu Pikkappikka III, Brave Dragon Elemental, Gil Fuji, Yokozuna)
Cards that are obvious references to development staff. (Examples: The=Deadman, Dragon Edge, Iocant, the Oracle)
Cards that require you to speak before they trigger an ability. (Example: Game On! Kirifuda Family!, Devil Beckham XXX)
Cards with perfume. (Examples: Idolmaster Leo, Onimaru "End", Grand Finale)
Errata. (Examples: Fuuma Vile Apostle, Perfect Galaxy, Spirit of Immortality (DM-28 Secret Rare))
Collaboration Cards.

Types of Trivia cards

1: Cards such as Aqua Master and Gaulezal Dragon are so weak that they are useless in actual gameplay, but due to their low card power, they had received a fanbase who treats these cards as gods (Sarcastically). For example, Scissor Eye, a Vanilla creature with below average card power, has received attention in the fandom and got a joke decktype known as "Scissor-Love" (シザー・愛, Which is a pun on "Scissor Eye") around it, which simply involves reinforcing Scissor Eye with Cross Gears. On the other hand, these cards are worthless without their illustration and flavor text, so this is one of the few ways to be entertained by weak cards.
2: Duel Masters is famous for it's work in cards that were not seen in other card games due to its high comical element after Psychic Shock, such as Cards made Of Metal, Cards made of 3 cards and Cards with perfume, which are attractive to players. There are also cards which are parodies to other franchises, such as Yattar Wan, Adventuring Fox and Storium, Light Ray Doll and can give a good joke to players who know these franchises.
3: Trivia cards which are also active members of the metagame, such as Überdragon Bajula being defeated by the vastly weaker (in actual gameplay) Wise Starnoid, Avatar of Hope as well as Perfect Galaxy, Spirit of Immortality which has it's secret version mistakenly labeled as a Spell. Due to an errata in Fuuma Vile Apostle's race, Grand Devils are often called "Dodevils".

They are an important existence in Duel Masters due to their opening of topics for players to talk of, and are a nice way to have fun save for dueling. However, overdoing it will often cause hate by players.

Notes

Cards such as Dolgeza, Veteran of Hard Battle, Syrius, Firmament Elemental and Alcadeias, Lord of Spirits are often considered trivia cards when they first appeared, but as their support increases they become easier to use.
The Episode Series, especially Episode 1 featured a series of cards with strange names that are never seen in the past, such as Red ABYTHEN Kaiser and Intense Vacuuming Twist (Dondonsuikomunau). While eccentric, they proved to be powerful in the metagame.
DMX-12 Black Box Pack and DMX-22 Super Black Box Pack are filled with Trivia cards.