Fans are entitled to fan based games, just as much as they are entitled to fan sites. Theres a limit to what fans are alloud and theres the fact that they can make a fan game but theres the fact that they are not allowed to sell it. If I were to make a fansite its just the same as making a fan game it has information about the theme and has things to do in the theme wich in this case is digimon. The fan can build, remake things but is not entitled to manufacture these fan goods for there own profit. This has ban debated to at many locations and its always ben agreed. Take a look at fpsc people make star wars fan games from that and none of them have ever ben sued. Yes digimon is a trademark name and all content in copyright to the company that invented them. But if they found a fansite for there content they would be happy, not want to sue a person.
A fan game is more of a tribute and a hobby more than a copyright infrigment. Same as if it were a fansite, or a built in fan rpg, like people make rpg mods in html for invision based on digimon, its all free that they make so theres no harm, theres a difference between fan based content and sharing illegaly stolen content, mostly because the fans content are there own content.
HAHAH tell that to nintendo they are shutting EVERY pokemon mmo down