Again, if I may, I'd like to add an extra comment. A soccer team is a group, but it's not a movement. I see a 'movement' as a group of people trying to achieve (ie move towards) some goal.
It makes little sense to speak of a movement without identifying its goal.
eg Tom has joined a movement to abolish capital punishment.
I agree with you. A movement is a group of people with common ideology who work together to achieve some goal. Equally, I am curious,though, in the given meaning, don't the members of a soccer team try to achieve some goal?: Winning the game.
I understand a movement is an organized effort or activity by a group of people to attain a certain social/political goal rather than the group of people itself.