Prioritize the following 3 builds and learn how to play them and you can compete with any bot/weapon combo regardless of level difference.

1st priority - KS with MR8. alightmotionapks.com   

You can run jav 6 until you get access to MR8 but don't invest heavily and make sure you have enough a-coins for MR8. www.kinemasterapks.com 

2nd priority - Guardian with PC8 

You can sub in ares/jug for guardian but guardian is a steal at 800 a coins so make sure you have a coins when he comes up on xp path. www.pandahelpers.com 

With guardians HP and ability you can outdamage carbines (even 12s) when use correctly. These are much cheaper to get then carbines and perform very similar.

3rd priority - panther with LA8

This bot and weapons come earlier than some of the others so feel free to invest a little to help get the resources for the other bots/weapons but this is last priority.

This is your bail out bot... you should focus on staying alive with KS and guardian.

MR8 and PC8 both have same/better range than carbines so you should not get outdistanced with anything save for LA.

If you learn how to position, kill bots from range, and stay alive with these bots/weapons you can legitimately compete with any bots/builds regardless of level.

Not going to lie.. I have spent money on the game (I wanted an arc torrent shadow lol), but before I did I would literally dominate people with much better gear than me with a MR8 KS, a PC8 ares, and a long arm panther. No reason. Why you can't do the same.