So I've been thinking of a way to make bum towers like: Necro, accel, sniper, paintballer, ace pilot, etc.
So how would synergies work?
They would force you to use weird loadouts to make certain towers have a better output.
(They only way these work are if these towers are in your loadout, not in someone elses, not if hacker clones it, not if your friend brings one of them, only if they are I your loadout)
For example if hunter and ranger on the same loadout:
Ranger: Hidden detection
Hunter: 30% cheaper
Brawler & Engi
Brawler: is way cheaper and gets hidden a level early
Engi: 10% more expensive but has a better output in mid game and late game
Sniper & Ace pilot
Sniper: Faster
Ace pilot: 30% more firerate, 10% more range
Accel & Farm
Accel: 30% less windup, more expensive early on
Farm: 5% cheaper, max level 20% more income but 30% more expensive
Electro&Tesla
Tesla: +1 placement limit
Electro: 10% range
Scout & Mini gunner (this may be too much)
Scout: 30% firerate
Mini gunner: 40% damage,10% more expensive (30 placement limit)
Medic & Commander
Commander: Unstunable,unfreezable, -3 seconds for cta reload
Medic: Uber charge lasts 25 seconds
Crook Boss&Kingpin
Kingpin: Hidden detection on max lower path,contractor spawns every 50 seconds and has. 170 lifespan, 10,000$ more expensive on max level
Crook Boss: 30% cheaper
Necro&Merc Base
Necro: gives Merc base damage buff on every Necro in a little range (based on the most upgraded Merc base) and also 50% faster
Merc base:
Rifleman: 10% faster
Grenadier: 10% more damage
Field medic: unit cap: 30
Riot guard: 20% more health
Mortar&Rocketeer
Mortar:200% more damage, 60% more expensive every level based on the last level increase
($1,$2,$4,$8)
Rocketeer: 30% cheaper
Gatling gun & commander
Gatling gun: 40% more damage
Commander: 25% max firerate boost
Cowboy & Kingpin
Cowboy: 10% more cash, 10% faster,10% cheaper
Kingpin: bounty cap up to 80K, Upper path hidden detection in max level
Warden & enforcer
Warden: 20% cheaper, 30% more damage, max level stuns last 2 seconds
Enforcer: Removes pump time on lower path, 20% slower,20% more damage, swat vans now have 2 lifes (after dying to an enemy they recover their full health and ignore the enemy they got killed by as if they has ghost and continue their track
Pyro & Rocketeer
Pyro: more damage and faster on max level
Rocketeer: 50% more splash Radius, 1s faster on max level
Freezer & medic
Freezer: 20% more damage, Unstunable, unfreezable, 20% cheaper
Medic: unfreezable permanently, Ubercharge also makes the firerate buff of medic 20% more
Slime trooper & Saboteur
Saboteur: 30% faster, poison slows more
Slime trooper: 50% More expensive, slows wayyyy more
Military Base & Juggernaut
Military: units spawn 20% faster, Rail gun tank slows close enemies, more expensive to max
Jugg: upper path 150 more damage
Lower path: 1.8x boss damage, max upgrade: 300,000$, 30 more damage
Soldier & Hacker
Soldier: more expensive, Hacker passively spawns soldier clones close to the track, they last 20 seconds, have 10% less dps, they also take 10 seconds to appear, soldier itself is cheaper and each level deals 5 more damage
Hacker: more expensive, Lower path has 10 synapses
Upper path: 200 more damage
I hope most of them are cool 
.
Many can be overpowered but I tried balancing them.
I think the idea is clear.
