Loosely following the original Duel Masters manga, which used cards from Magic The Gathering instead of the Duel Masters cards (which were created for this series, thus explaining the similarities), the anime is what helped the Duel Masters franchise to hit the main stream.As explained on Duel Masters main article, the anime is completely different whether you are looking at it from the Japanese version or the North American version. While the former is a serious series about a children card game (not unlike the series which inspired it), the latter is the Ur Example of The Abridged Series in all but longevity.The story revolves around Shobu Kirifuda, an enthusiast of the titular card game who is exposed for the first time to a higher level of play (referred to in the North American release as Kaijudo, literally "the way of monsters"; it wasn't given a name in Japan), in which actual monsters serve the will of their summoners. As his father had mastered the game before him, Shobu feels a certain need to live up to his family's reputation.There is one America-exclusive season which revolves around our protagonist fighting against a Goldfish Poop Gang. The Japanese version, instead, continued to run for 8 seasons with To Be a Master as a central point. Shobu was later exchanged as a protagonist with his smaller brother.Please note that most (though not all) of these tropes are either common to both versions or are otherwise based on the North American version. The original Japanese, while still having comedy, played it straight for the most part.
Anime Hair: Referenced in the dub's theme song and the subject of many a Lampshade Hanging, though Shobu's hair could probably support an actual lampshade. Hair is Serious Business second only to the card game itself, especially among Shobu, Hakuoh and Kokujo.
Breast Expansion: Mimi's breasts get larger from episode to episode in the first season. The American first season actually toned this down. By the way, she's underage. Though the dub did make reference to it in a late first season episode when, as the girls were expressing relief that a possible cancellation of the series had been averted, Mimi commented that she was enjoying her new curves. To a lesser extent, Sayuki also gets noticably bigger as the series progresses.
Catchphrase: Anything about "owning the zone", as well as a number of overused traditional Japanese phrases.
Charles Atlas Superpower: Mimi demonstrates on several occasions that she is quite proficient in martial arts and far stronger than she looks.
Combined Energy Attack: In the American-only second season, the five creatures Shobu recovers are invoked by his friends to defeat the PLOOP.
Cultural Translation: The Gag Dub, as well as the North American-only second season. Eventually, later card game expansions started using flavor text based on said Gag Dub.
Cross Over: The Duel Masters movie (Curse of the Death Phoenix) saw a release in tandem with the Mega Man NT Warrior movie (The Program of Light and Darkness) (only in Japan). In Program, Netto and company are at an expo, where they catch Shoubu summoning the Bolmeteus Steel Dragon; in Curse the same crew are in the tournament stadium, cheering him on more directly. While in the movies themselves only contained brief snippets of the other's footage, both Shobu and Netto (as Rockman R) worked together in the opening cinema. Also, Mega Man Battle Network 5 saw a set of Giga Chips with the powers of the Eternal Phoenix (just named "Phoenix" in game) and the Death Phoenix, whereas Forte.EXE got a pair of cards in the DM game. (Same card, different artwork, technically).
In Kintaro's introduction episode in the dub, a reference is made to a "www.noveltyflyingcapes.com", which sells, well, novelty flying capes. During the shows run, there was actually a page at that address, featuring a picture of Hakuoh with his cape, and information on where to get the capes—for 50% off, you can tell them Fritz the Bitter Goblin sent you. Unfortunately, the page is long gone. An archived version still exists, but all that's visible is the aforementioned information.
Did You Die?: In a flashback, Shobu loses a Kaijudo duel, and possibly dies. In the dub, the person listening to his story wonders if he might be a zombie.
Shobu: What do you want me to do? Not eat a brain?
Disappeared Dad: Shori Kirifuda. It turns out he's the guardian of the Fire Civilization.
Door Roulette: A sequence with Mimi walking through the temple became this type of scene in the dub.
Evil Twin: Subverted and lampshaded; both twins are evil, and both try to convince Shobu that the other is their evil twin.
Lucky Translation: The English dub had Benny claim that Mimi was his little sister, completely unaware that they would actually show his sister (possibly unrelated in the original) in a (fake) flashback. As chance would have it, Benny's sister looked exactly like a young Mimi. Word Of God from a post on the Toon Zone Forums.
The shades-wearing pajama-clad baby is named Jouji in Japan. This was easy to translate to George for the dub, and plenty of Boy George references quickly followed.
Meaningful Name: Shobu (勝負) means "challenge" or "game"; Kirifuda (切り札) means "trump card".
The Music Meister: Remarkably for a Japanese work (where Musical Episodes are uncommon in the first place), Duel Masters Victory V3 has an episode about a wannabe singer whose magical companion causes others to break out into spontaneous shouts, and eventually, singing and dancing. The main characters even sing the jingles during the eyecatches.
White Hair, Black Heart: During his tenure as the temple champion in the first season, Hakuoh sports bluish-white hair and a very sour attitude. Once he undergoes a Heel-Face Turn, his hair shifts to blond.
Wild Take: Babylike George actually has to change his diaper after every surprising twist. Several dub seasons edited this character quirk out.