This is my perspective on them:

Light SMG Ground: They are easy to destroy, but can cause havoc if caught by surprise.

Role: Flanking, Objective taking, Responding to Base attacks, backdooring

Counter with Plasma flyers. Generally weak against Rails and Head on confrontations

Medium SMG Ground ( 8-12 SMGs, 4-5 layers of armor): Bread and butter of any team. These can do anything, but nothing particularly well

Roles: General purpose

Counter with Heavy SMG ground, generally weak against Rail

Heavy SMG ground (12-16 SMGs, 6-8 layers of armor): Moving fortresses. They are really good at up close fighting

Roles: Objective holding, damage soak

Counter by avoiding direct SMG confrontations and plasma bombers. Generally weak against Plasma.

Medics: Not much to say, these are high value targets that should be focused at all times

Counter with Rail, generally weak when focused

Plasma Ground: These are excellent objective takers as they can destroy towers in seconds and get around unnoticed

Roles: Objective taking, Backdooring

Counter with Rails and Medium SMG, generally weak against direct confrontation

Plasma Air: These will be dishing out a ton of damage that is very difficult to avoid and retaliate from

Roles: Fire support, Responding to enemy positions, Scouting

Counter with Rails and Interceptors, generally weak against Pings

SMG Helicopter: While fragile, these have access to the roofs of ground vehicles and can quickly destroy them, or be destroyed if discovered first

Roles: General purpose, Flanking

Counter with Rails, generally weak against pings.

Rails: Fantastic anti-air capability while able to burst down crucial targets from a safe distance.

Roles: Disabling enemy bots, destroying small targets, Anti-Air

Counter with taking objectives, generally weak against pings, flanking and rushing.