Martial Tank is powerful but slow. Using well-timed rolls or just running around the foe is more than enough to dodge its attacks and keep behind it. Tri-Thundaga is the best method of attack against it, but if that's not available, using any Lightning-elemental attacks or Punch-type attacks will work as well. When it gets low enough on HP, it'll use Eject! to summon 5 Support Machine+ enemies. If the player is using Tri-Thundaga, just continue to attack the Martial Tank with it to defeat it as quickly as possible.