Digimon: Digital Monsters

Seven kids are transported to the Digital World, a strange place where digital creatures called "Digimon" reside. A group of Digimon soon befriend them and keep the kids out of harm's way. The children then discover they are the Chosen Children, which protect the Digital World from evil Digimon like Devimon and Vamdemon.

Yu-Gi-Oh!

Yu-Gi-Oh! Duel Monsters centers around the journey of the spirit of an ancient Egyptian pharaoh who is trying to re-discover who he was many years ago, since he has lost his memories. With the help of a boy, Yugi Mutou, the one who awakened the spirit, and his friends, he battles many villains and adversaries. Many of the villains have been linked to the Nameless Pharaoh's past, due to the Millennium Puzzle he holds and many try to take the puzzle and his power away from him. The series focuses on the card game aspect of it and the main theme represented throughout the series is friendship.

Yo-kai Watch

Animated adaptation of Level-5's Nintendo 3DS video game. While going deeper into the woods one day, primary school student Keita Amano ('Nate' in the English localisation) notices a bizarre capsule toy machine who tells him to insert money which he obeyingly does. But after opening the capsule that came out, a ghostly creature named Whisper materialises. Whisper, who was sealed inside the capsule, rewards his liberator Keita by becoming his Yo-kai butler and gives him a Yo-kai Watch. Whoever wears the watch gains the ability to see supernatural creatures called Yo-kai, each type possessing different kinds of magical abilities, and which are normally invisible to humans. The Yo-kai Watch also allows the wearer to summon any Yo-kai they have befriended, enabling the wearer to make use of the Yo-kai's powers. Using it, Keita and Whisper encounter many mischievous Yo-kai around town, resolving the trouble they're causing and befriending many at the same time.

Medabots

In the near future, humans and robots coexist. “Robattles,” a competition in which Medarot are pitted against each other, is popular among kids. A Medarot’s consciousness, effectively its brains, is located in a Medal that can be inserted into and ejected from the robot body. By chance, nine-year-old Ikki finds a Rare Medal, and soon after has his own Medarot named Metabee. This is the story of their friendship and growth as they use wisdom and courage to fight countless opponents in robot battles.

Digimon Fusion

Taiki Kudou, an upbeat seventh-grade boy who always helps people in need, encounters a Digimon named Shoutmon, who brings him and his friends to the Digital World. With his friends Akari Hinomoto and Zenjirou Tsurugi, they form Team Xros Heart to compete against rival teams battling for supremacy, with their ultimate goal of taking down the evil Bagura Empire, who plans to conquer the Digital World. (Source: Anime News Network)

Digimon Frontier

Takuya Kanbara is an average city kid who receives a text message from an unknown source instructing him to "board a train towards his destiny". Taking up the Call to Adventure, he finds the train in question and is whisked off to the Digital World, which is currently under threat from the malevolent Cherubimon. Cherubimon and his minions are consuming the very building blocks of the Digital World (its "Fractal Code") to increase their own power, and if nothing is done then the entire Digital World will be devoured. All is not lost, however. Takuya and the other "chosen" children who boarded the train inherit the power of the Ten Legendary Warriors that saved the Digital World in the distant past, allowing them to transform themselves into Digimon. With their new powers, they fight to take back the stolen Fractal Code and restore the fractured Digital World to its former glory. (Source: TV Tropes)

Yu-Gi-Oh! GX

Duel Academy, one of the most prestigious schools in Duel Monsters history. There, students learn the fundamentals of becoming not just duelists, but large business owners. Judai Yuki is a new student with only one thing on his mind: to become the next King of Games. Judai meets several friends, teachers, and even enemies at the large Dueling school. There, he'll have to face off against several different dorms&mdash;Slifer Red, Ra Yellow, and Obelisk Blue&mdash;to become the number one duelist. Will Judai be able to pass all of them? Based on Kazuki Takahashi's world-famous anime and manga, Yu-Gi-Oh!</cite>.

Digimon X-Evolution

A virtual world was created by the present-day network called the "Digital World". The "Digital Monster", which is a digital life object, was born, and the host computer Yggdrasil managed the different Digital World areas. However, it developed the X Program of fear to eliminate all Digimon in the old world and develop a new Digital World for only certain Digimon... Now, the greatest crisis ever approaches the Digital World. The X-Digimon, a new type of Digital Monster, is hunted by the Royal Knights who protect the Digital Worlds. Their master, the network overseer Yggdrasil, seeks to set in motion Project Ark to renew the Digital Worlds and create new Digimon, but at the cost of all other digital life. This new X-Digimon will seek out the answers to its own existance as it tries to protect the life of all Digimon, and in the process it will change the Digital Worlds forever. (Source: Anime News Network)

Digimon Data Squad

Masaru, a second year Junior High student and undefeated street-fighter, is about to learn the meaning of the word "teamwork." After Agumon escapes DATS, an organization that deals with Digimon, it winds up in a fight with Masaru. Soon Yoshino and Lalamon come to capture Agumon, and the two fighters escape. After an evil Digimon appears, it's up to Masaru and Agumon to defeat it with their DNA Charge. Soon, Masaru must join DATS to put an end to the Digimon coming to Earth. With the help of Yoshino, Ikuto, and Touma, the group must stop any evil Digimon that appear, and return them to the Digital World. But not everything goes as planned...

Shadow Star Narutaru

During her summer holiday at her grandparents house Tamai Shiina, a young and cheerful schoolgirl, meets a strange looking creature. They befriend each other and Shiina names it "Hoshimaru - The Round Star". When Shiina returns home after the summer to go back to school she starts meeting other kids that also have befriended a strange creature like Hoshimaru. But she soon finds out that not all these creatures and their masters are as friendly as Hoshimaru. (Source: Anime News Network)