I am assuming you mean support type bots?
If so most support bots are fairly balanced so its more just your own personal choice. Plus they have no weaknesses (They can get all damage reduction carts). However they do not excel anywhere really.
My personal favorites are:
Bugsycait + Burst Fire Bit(Or repair bit if I feel like playing pure support) + Whatever laser and explosive weapon you like.
- His shock shield is awesome for dealing with the melee rushes that will eventually happen to the ARTs on your team.
- The Burst Fire Bit + Bazooka or other explosive weapon is great for driving off AIR types, just have to watch your ammo.
- The Burst Fire Bit + Things like the beam machine gun will eat through melee deprived lands at an amazing rate. (Of course most other beam weapons would work too)
Winberrl + Dual Shotguns or Zooka + Burst Fire Bit or Long Range Bit (Once again repair if you want to play more support)
- Her drawguns make it extremely easy to single out someone from the group and pull them into yours (Generally everyone shoots the snared bot)
- The drawguns also make it very easy to pull someone in and blast away with your weapon of choice
- The Burst Fire Bit will make you do a lot more damage and pull them in faster but you need to be careful of draw gun ammo (Its fairly limited)
- The Long Range bit will just let you snare them from farther away making it easier to single out someone.
Also I have seen amazing things done by Dharma Star (I have not used one yet though)
These are just a few of the things I have noticed in my short time playing this game, keep in mind these are purely my opinions and I am fairly new to this game lol.
Anyway hope this helps a bit