While it's a creature, Gruul War Plow gives itself trample.

While it's a creature, Gruul War Plow has creature type Juggernaut. It doesn't have any abilities associated with the card named Juggernaut.

A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of his or her most recent turn. It doesn't matter how long the permanent has been a creature.