Have at least 1 pet with an overall rating of 100 or more - Where this option is? And someone could rate my pet ^^?

Rating has nothing to do with other users, it has to do with the stats of your Pet. :)

An overall rating of 100 means that the stats of your Pet (Apart from Intelligence it doesn't count!) must reach 100 or higher when added up; to raise stats you have to train your pet at the training center that is located at Riverside Valley.