Charisma can be used to block an enemy's attempt to Move out of the occupied position. This may be done freely; it is not considered an Interrupt or any other kind of play. However, only one entity may attempt to block another entity's movement; in the case where multiple allied entities wish to block, they must decide among themselves who will perform the roll. If players cannot come to an agreement, the DM will choose for them.
When an entity attempts to use Charisma to block movement, both the moving entity and blocking entity perform an opposed roll using Charisma. Ties are in favor of the moving entity. If the blocking entity wins the opposed roll, the moving entity is blocked and loses that Move. If another effect grants the entity another Move, an enemy (including the same one as before) may attempt to block it again, prompting another opposed roll.
Movement can be blocked even if it functions similar to a Teleport in that the moving entity can reposition anywhere on the Stage. Opposed Charisma rolls represent getting and holding someone's attention through force of personality rather than physically impeding someone's movement (though in some cases this may be a proper interpretation of events).
For more information, see Player's Guide Chapter 6: Interaction.