[Muse]

Coordination will occur if all armies deployed in the movement phase arrive at the target province. (They will form one large army, with scripting and positioning intact.)
Individual armies can be delayed by *bad things* happening to them before the movement phase. Commander assassinations, Magic-Phase-Murder, all. Even being intercepted by a 'faster' army during the movement phase.
The same will occur for all units teleporting to a province in the magic phase.

Coordination will not occur between phases-- magic phase battle, then movement phase battle. (Two separate armies, ostensibly.)

As a slight note-- questions that are easily tested in the game, or by Wiki/FAQ searching may draw the likes of Calahan (or other stealthy watchers) to rend your mind from its vessel in a flurry of deathly sharp glares.

Though! I am quite glad you enjoy the game! New blood is nearly always welcome.