Go to strategy go to OL (click R like 2-3 times) set to use it. During battle just make sure they use an arcane arte. --- Official Apollo Justice of the Professor Layton vs Ace Attorney board AMERICAN Thread: http://www.gamefaqs.com/boards/975212-super-street-fighter-iv/56061026
It's easiest to, when the AI activates its Overlimit, to just switch to that character and do it yourself. You'll only be away from your main for a few moments, so don't fret. --- The official Matt Engarde of any board on which I post.
Almost 99% of the time, if they use their Overlimit and have enough TP to use an arcane arte, they will use their Mystic Arte; they're programmed to automatically use the Mystic Arte if they complete an arcane Arte during their overlimit. You have to actively go out of your way to prevent it; since the "Use it" overlimit strategy is the default setting, and you would have to disable their arcane skills to prevent them from activating a Mystic Arte.
But every character has a more powerful Mystic Arte they can use under special conditions; and getting them to use that particular Mystic Arte requires a conscious effort on your part. These Mystic Artes are only available on a 2nd or more playthrough, you can't use them on the first playthrough.
Luke: Lost Fon Drive. Must be equipped with the Sword of Lorelei, Luke's Health must be less than 15% of it's maximum, activated by pressing Y, B, and A all at the same time. Radiant Howl Extension. Only possible if Ion is in your party during the story 2nd playthrough or later, Hold A while using Radiant Howl and Ion will appear to use an attack identical to Synch's Akashic Torment. This was known to cause the PS2 version of the game to freeze occasionally.
Tear: Fortune's Ark. Must have used every Fonic Hymn at least 50 times in battle. Activate using Judgement while in overlimit. Hold A during the Mystic Arte to activate an extension that does extra damage, and heals and buffs your party.
Jade: Indignation. Must have used Thunder Blade 200 times in battle. Activate using Thunder Blade while in overlimit.
Guy: Brilliant Overlord. Must have used Final Cross 150 times in battle. Must be equipped with the Jewel of Gardios, must have low health. Activate using Final Cross during overlimit.
Anise: Dying Moon. This is an extension to Final Fury, activate by holding A while performing Final Fury. Was known to cause the PS2 version of the game to freeze occasionally. Fever Time. Must have used Lucky at least 100 times in battle. Activate using Lucky during Overlimits. If Fever Time doesn't cause the battle to end, then you will lose 20,000 Gald.
Natalia: Noble Roar. Must have used Piercing Line at least 150 times in battle. Must be equipped with the Elven Bow (exclusive to Din's Shop in Chesedonia). Activate using Piercing Line during overlimit. --- QI, the only fake gameshow that will take points away from panelists for false positive answers in previous episodes.
You must have the Moon Selector key item first; which you get during the story from Miyagi in Baticul before you enter the abandoned factory. Once you have the Moon selector, you can switch characters while in battle by opening the menu with X, and then pressing either Start or Select to rotate through your characters. --- QI, the only fake gameshow that will take points away from panelists for false positive answers in previous episodes.