Monster Rancher EVO is totally unlike any other games in this series, so fans beware, this may not be what you expect!
Like the previous Monster Rancher titles, EVO does involve raising monsters, but that's where the similarities end. Gone is your ranch and in its place is a circus. You are still a monster breeder, but raising your monster is now a group effort. You train your monsters each day to perform tricks for a circus show, and they only gain stats (Life, Speed, Strength, etc.) during "Showtime."
Shows are performed once every few months. Performing shows is necessary for monster growth and circus popularity. Increasing your popularity will enable you to move the circus (and advance the plot) into other areas of the game.
In addition to "Showtimes," the game also includes "Adventures," which those familiar with the series will remember. You go on adventures to obtain items necessary for mini-quests (there are many of those) and to further advance the plot. These adventures are full of challenges and ways to improve your monster, as in the other MR games.
An important thing to remember about this game is that you are not the sole trainer. In face, you do very little training because you assign others in your circus group to do it for you. That being said, MR EVO is a very plot-oriented game, with less of an emphasis on combat than its predecessors.