On early game, Yapyap is excellent at harassing enemy units. Since Yapyap is a disposable unit and can be produced as many as player wishes for, use it to explore and act as a scout. Though be wary as it only consumes the population.
Goblin is a very difficult hero to beat without proper strategy. With three goblins around, the Grunts can use Hustle and keep themselves alive most of the time. Note that Energy Shield recuperation will not be affected by Hustle.
Grunt Dome leader power is effective to counter several leader's offensive leader power. A maximum level of Grunt Dome can resist Eradication leader power if used correctly.
Guilt Trip affects all players units and it can prevent the enemy to gain veterancy faster. Though be careful as several leaders, such as Captain Cutter's Battle Hardened Leader Power can counteract it as it can accelerate the veterancy rate.
Shade Drop Leader Power is extremely annoying if used correctly. Although it has a set of duration, it's enough to harass the enemy.
Please Don't Shoot Me was a double-edged sword. Use it wisely as it can give either benefits or disaster to you.
During the duration, any non-offensive leader power can be utilized.
Note that this means Nightingale and Huragok can heal wounded units during the duration without the worry of attack by the enemy.