A Remove Magic spell only affects enemies. Despite what the Description says, levels of the magic being dispelled don't factor the dispel success rate, only level-differences among the casters count. This spell checks effects from different casters individually, meaning that effects received from a high level caster are less likely to be dispelled than those from a low level caster when all are present on the same person. The target's Magic Resistance, if any, does not affect this spell, the only way to defend against it is Spell Immunity: Abjuration.