Requires skills of either Stroke of Genius, Rebel Yell or Intimidation. These skills do stack alongside one another, so having a team of heroes with all these skills would make sense. Stroke of Genius and Rebel Yell are Intellect based, while Intimidation is leadership based (for increasing trigger rate). Each skill will reduce thhe heroes defense by 5 points per level of the skill. Try to put one hero in charge of each skill, providing them the best gears for increasing effect and launch rate. Also provide that hero all the training scrolls for that skill. Training scrolls for these three skills can easily be found in the stand. Max out your intellect or leadership based on which skill the hero is running.
Gears: Equip gears that primarily boost the effect and/or launch rate of the particular skill equipped on your hero. Next you want to focus on leadership, (and intellect if you're using Rebel Yell or Stroke of Genius). Why leadership? So you can strike the target before all your other teams move and strike it. The defense is reduced on the hero struck until the end of the next round. So the sooner you can apply it, the sooner the advantages you can take of it. Next you're going to want to look for infantry or troop defense reducing items. (In HC level 89 there is a ring that reduces infantry defense, for other gears try to refine the stat on) Typically the heroes you need to reduce defense for are using infantry (Zhou Tai and Zhao Yun).
Beasts: Try to increase your attack power primarily.
Skills: (Assuming we're dealing with the typical T3 class infantry hero) Linebreaker is a must. It can be found in the Historical Campaign map "Battle of Guan Du" Heavy Sword is a rare skill you can find in events and possibly the school. This will also increase your damage against infantry. Yin Yang and Archer Commander (assuming you're using archers) are great skills to help increase your offense because there is no skill that counteracts them. Heaven's Blessing is a great way to reduce your opponents defensive skills like infantry guardian and adamanta. Homing Strike is a great skill to ensure you strike your opponent, since it reduces their dodge rate. Clouds and Mists, and Piercing Arrows will help increase your critical strike rate and damage.
Madam Xiahou and Queen Mother Bian can also help assist with increasing critical strike rates and damages as support heroes for your team.
Trials and colored stones can help increase your ability to further damage your opponent or increase your critical hit rate.