This sounds a bit out of our period or at least at the very end. The formation was called a Tercio and was a block of pikes, 4 blocks of arquebuses - one in each corner and often a couple of other units such as sword and buckler men or light guns. This was the basis of the Spanish army in the 1500's. The concept was that it was like a castle. The pikes were strong - about 1000 men and armoured. The shot units were about 200 strong and were in each corner of the pike unit, like turrets on a castle. The sword and buckler men were about 200 strong and were meant for attacking the flanks of opposing pike blocks. The light guns do not really have a unit like it in MTW, as they were manhandleable and moved with the infantry. The unit evolved into the pike and shot units of the Thirty Years war and English Civil war of the 1600's mainly by arquebuses becoming muskets, pike numbers becoming less and proportion of shot becoming higher. A typical unit would be 200 pike and 2 units of 200 muskets, one on each flank of the pikes. A salvo from the Swedish muskets in the 30 year's war would stop an armoured cavalry charge dead in its tracks.
All this sort of change and the range of different armies across Europe and the Middle east all shows how great a Renaisance Total war would be. Throw in religious conflict, Islam, devious deplomacy and it would be a great game. SPI had a great 6 player board game called "A Mighty Fortress" many years ago, the highlight of which was when Protestant missionaries faced up to the Jesuits in Theological debate with the loser being burnt at the stake!! So come on Creative Assembly, how about it??