Rounding issues with quick attacks

I read this remark in a posting by Data10, and it really opened my eyes:

"For example, I powered up my attacking B/SE Tyranitar to level 33. I chose level 33 because that will allow me to fight up to level ~35 Blisseys with Bite rounding to 5 damage instead of 4, which is the strongest Blisseys I've faced in my local gym meta. And getting that 5 damage from Bite instead of 4 will reduce battle time by 10-15 seconds, which is very important against Blissey."

Normally, i ignore those rounding issues, because they are hard to calculate with, but they seem to be quite relevant.

The example given above is good - rounding in Battle gives whole numbers of damage delt for each attack. If calculation gives 4.4 damage, you would deal 4 damage, if calculation gives 4.6 damage, you would deal 5 damage, each time a quick attack deals damage. In this example, difference is huge - 25% - as much as being super effective or not.

[Edit]
Correction - as in damage formula "floor" is used instead of "round", the example should have been 4.9 versus 5.1. Thanks to blue-333
[/Edit]

This effect is the more important, the smaller and faster an attack is. It can be completely ignored for charged attacks. It should be concidered for quick attacks with up to 9 damage, above the effect is smaller.

How can we use this in praxis? As damage is calculated out of level dependend attackers ATT-Stat, defenders DEF-Stat as well as SE and STAB, it depends highly on the matchup. If you have a generic attacker as lick-snorlax, you have so many different matchups, that this effect is middeled out over many battles. The interesting part comes with repeating specific battles - as Data10 writes, Tyrannitar versus level 35 Blissey. Another interesting matchup is venussaur - vaporeon. In the range between level 30 and 34 Venussaur and Vaporeon, either 6 or 7 damage are delt with each Vip Wine. So - for me - it makes absolutely sense to raise my Venussaur to level 34, as it is likely to be noticeable better in its favorite matchups.

An easy way to test those specific matchups is PokeBattler. After simulation, you can look into the battle log and see how much damage is delt with your quick attacks. Then you can vary attackers and defenders size and maybe you notice such a step, making you rethink leveling beyond 30 or not.

Regards BB