Any of those spells alone could win the battle if strong enough, so we must assume reasonable limits.
Typical rumored limitations on telekinesis limit its effectiveness to:
- things that are not held by a living being
- the above AND things that can be yanked away (weapons)
Bring primitive (no arrowheads, etc) bows, arrows and spears made with freshly cut plant material. Even common poplar and willow stay alive a LONG time after.
If you're paranoid, do the same with clothes - armor won't be of too much use anyway, except against Morritiw's sword.
Best case: Ghuvj attempts TK on the arrows (or ignores them in favor of offense - weird, but don't be overconfident, king!), Morritiw's shockwave fails to work due to the arrows' aerodynamic profile, both mages die.
Worst case: Ghuvj and Morritiw cooperate and are quick to catch on, a wall of earth saves both from the volley but cuts off their field of view and pins them there.
That's a good start.
Assuming both mages live:
A cautious probing attack is just a waste of soldiers.
An immediate all-out charge (from both sides of the wall, neither lining up (lightning) nor clumping (fireball, shockwave) will likely be a win, though at cost.
Keeping distance provokes ranged fireballs and lightning bolts. What defense could we have against those? A saline-soaked heavy cloth held on dry sticks could fall prey to TK, though, assuming you're not strangled with it, that at least would mean no fireball the next few seconds.
But getting into ranged combat with mages in cover feels like a bad idea anyway, so - charge.
As for protecting the king? maybe not let them know which one IS king? Just an archer giving suppressive fire; have the knight bark orders.
Yes, there are loops upon loops in this plan, but no plan survives contact with the enemy, and we don't know the stats (magnitude, range, damage, AOE) of the spells (could TK be used to push the wall of earth? Could the shockwave send pieces of it flying? How quickly can a different spell be cast?), and we can only assume everything about the environment had already been mentioned (e.g. that it isn't an option for the royal side to go into debt to hire mercenaries, or that we don't need to worry about vulnerability in the hours following the battle) so it's hard to tell the BEST way to proceed.
There is always risk. Turtling the king is a sure loss, so we must hope he isn't engulfed by a one-hit-kill 30" fireball in the first second.