This is quite a problem actually. Personally, i'd rather see myself as a Nid warrior/fex with 20 followers: gaunts and rippers. When i march through the ruined city i see my pets swarming around me, jumping ontop boxes, climbing walls to some extent. Then, i see 10 marines walking out of a dark alley. The first thing i do, is i make my pets charge the marines, and attach them with a Venomcannon or whatever Chrome feels like giving me. The marines divide their attacks on me and the bots. after a few marines are slaughtered, but also my swarm is, i fold out my whip, my sword and my scythe tail. And take on the marines.
Ok what you are saying is you want every player Nid to basically have an army, which I understand. But also remeber that this is a game ON THE INTERNET so lets say we have 6 player nids. Now lets do 6 times 20 which is 120 bots plus the 6 players. Then lets say you have 18 marines on the other team. It just keeps adding and adding up. This would probably make the game extremely laggy and unfit to play.
Player nids shouldn't have more than 3 AI partners. And these AI nids should have the same HP as a marine buy only do 35% of the damage a player nid dose. An a player nid should be able to kill a marine in 1-2 hits. So lets say marines have 125 Hp, the player nid should do around 115 and after that the 3 AI nids should be able to kill it easy.