So, I tested leaf bombs... but even cheating later and giving myself 10 power throw and the 65p base damage bomb, they all do zero damage... if I am really, really lucky, they deal 1 or 2 of damage to very light armoured enemies.
Leaf bombs don't have much splash, you have to hit the enemy dead on to do significant damage. However, they also can cause those directly hit by them to go berserk, attacking nearby troops even if they're friendly.