You fight this joker three times, but only M5 is compulsory.

1. Right after the battle starts, attempting to hit him with your sword now will not work since he will teleport away immediately. Shoot Vergil's Summoned Swords at him continously as you walk in his direction. Try to Stinger him from time to time and look carefully for when Jester stops for a breath, then Stinger him immediately. Once hit, you will be given some time to continously attack him.
    
2. After Jester takes a good number of hits, he will teleport away and summon magical balls of energy that bounce all over the place. To easier avoid these, stay at the perimeter of the battlefield and jump when you see any of the energy balls coming at you while you keep shooting with Vergil's Summoned Swords.
    
3. After a while, Jester will dispel the energy balls, then repeat step 1. Note that Jester takes less damage, sometimes even none, when he is inside his barrier.
    
4. After that, Jester will summon his magical energy balls again, but beware. It may not be the same as in step 2. He has another pattern of energy ball attack where the balls fly across and out of the battlefield from where Jester stands. In such cases, run towards the perimeter of the battlefield and make sure you are in Jester's frontal direction. Jester will then send rows of energy balls flying at you. Look out for if the next row of energy balls appear from the top or bottom. If bottom, jump, if not, you can stand and wait.
    
5. This continuation applies to mission 12 & 17 Jester battles:
    
   In M12 and M17 optional Jester battles, Jester is stronger and has additional moves. After taking about 50~75% of his life, Jester will summon a big round ball with a face. I will call him face for clarity sake.
    
6. The face is capable of doing a few different moves. The moment Jester summons face, he will remain standing on top of it, which means to hit him you will have to perform aerial attacks. However. as usual, always keep shooting at him from a decent distance with Summoned Swords first until you see him tire out. Then, get close to him quickly by using Trick Up and start slashing with Aerial Rave.
    
7. When hit, there is a chance Jester will disappear from the face. When that happens, run away from the face for it will explode. Jester and a new face will almost immediately reappear from the skies so be careful as not to get hit by the falling face, then continue step 6.
    
8. The face also has other moves of its own. Sometimes it will form a red barrier that divides the battlefield into 4 sections, leaving you stuck in one as Jester summons his magical energy balls. Try your best not to get and use Devil Trigger to reduce damage if you are not confident enough. Occasionally the barrier will also move around the battefield so you will have to move along with it as well.
    
9. The face also has a move where it shoots out a red ball from its mouth as Jester summons his bouncing energy balls. To avoid it, jump in time and make sure you don't get hit by the boucing energy balls as well. And perhaps once or twice in a battle, there will also be a red hand that appears from the ground to grab you (like those of red sealed doors), so keep running away as you dodge the energy balls. The best way is to run around the perimeter in one direction and jumping out of the bouncing energy balls' way.