Super Smash Bros. (series)

The best way to describe this series is straight from the experts, those at the Smash wiki.

Quick Summary
Super Smash Bros. is an incredible fighting series by Nintendo. It pits many of Nintendo's legendary characters against each other in an all out battle to the death. Fighting on many unique stages, players use a huge variety of characters to beat up and KO their opponents to win in various match styles. They may use items as they come and a carefully planned out set of moves to best their enemies alone or with friends. There are Target Smash stages to try winning, and many trophies and stickers to earn. Each game has its own campaign mode to sharpen the players skills, and a bunch of hidden goodies to enjoy when not fighting. Definitely a famous enough game to inspire you all to try your hands at a sequel.

Benefits of basing your game off these ones

 * Most of the game revolves around fighting, so articles are already part way done once you start.
 * Most changes include adding a few stages, classic mode, an adventure mode, new Pokemon/Assist trophies and a new way to earn trophies outside of fighting.
 * Not too many changes each sequel

Limitations to keep your game believable

 * Nintendo characters only, very few exceptions
 * Not too many changes each sequel