Rikken is fought alongside Elza and six pirates on of Trial Mode Stage 86 in the Zodiac versions of Final Fantasy XII. This is considered one of the harder stages of the gauntlet. The following weapons can be stolen from Rikken during the battle: Durandal (uncommon) and Simha (rare).
Battle[]
Stage 86.
Rikken opens with Enrage, making his attacks not take any Charge Time to execute. He has the Ignore Evade passive ability, making shields against him pointless. At half HP, he uses Battle Cry to strengthen his attacks further, and at critical HP gains the Reduce Damage and Low-HP Def+ augments, greatly reducing the damage he takes.
Strategy[]
A good strategy is to use Warp (either the spell or Warp Motes; equipping an Indigo Pendant makes Warp always hit) on the Pirates, then blind Rikken and berserk Elza. The player can also summon an Esper to act as a decoy, as they tend to draw in all enemy attacks.
Rikken's HP Critical phase may drag on due to him resisting damage and attacking non-stop, so the player may want to go all out with Quickenings and perhaps use a Dark Matter on him.