Alright so I got some babies ideas. Of course, I'll let you fine tune the balance of it all, I'm just trying to come up ideas I haven't yet seen in my few runs (hopefully, I didn't suggest something that's already in the game or suggested).
Lil' Brim - costs: 200hp (4 hearts) - recharge: mediocre - Lil' Brim charges up a strong blood laser that damages all enemies on its lane, but will only fire it when ordered to (by clicking on it). It costs 50hp to fire (to mimick dark bum/magnifying grass a bit), and has some medium/long cooldown between shots.
Robo-baby - 100hp (2 hearts) - recharge: fast - Robo-baby fires weak lasers, targeting the closest enemies on 3 lanes (his own and adjacent ones). The lasers pierce through all enemies, dealing weak damage in an instant (think Lightning Reed x Laser Bean).
Robo-baby 2.0 - 125hp (2.5 hearts) - recharge: fast - Similar to Robo-baby, Robo-Baby 2.0 fires piercing lasers, but only in its lane (forwards/backwards) and up/down, if there are enemies there. It also fires faster than Robo-baby.
Battery Baby - 150hp (3 hearts) - recharge: slow - Battery baby creates an electric 3x3 aura around itself, dealing constant damage to all enemies around it.
Ball of Bandages - 25hp (0.5 heart) - recharge: mediocre - Ball of Bandages acts as a weaker cube of meat, however you can put a ball of bandage ontop of another to upgrade it. It has 3 levels, gaining health on the second and the ability to shoot on the third.
Tumor - 50hp (1 heart) - recharge: fast - Tumors can only be placed onto any other tower, slowly shooting at enemies in its lane. Moreover, Enemies will eat the tumor before the baby. However, babies carrying tumors are slowed down (like a speed down).
Mini-monstro - 150hp (3 hearts) - recharge: fast - Mini-monstroes periodically fire a burst of tears on the 3x3 tiles in from of them.
Oh and also a boss idea: the Archbishop. The Archbishop looks like a buffed up the Bishops from Repentance and stands at the far right side of the room, occasionally spawning enemies. All lanes can target it. The boss protects enemies on the field (again, similar to bishop enemies), taking damage itself in the process. After taking a certain amount of hits/damage, the Archbishop will be stunned for a moment, protecting himself but leaving enemies vulnerable (your chance to clear the board). The Archbishop might also shoot tears against your defense during phase 2/3.
(also plz put almanac for enemies and make the shovel animation for cube of meat cleave it thx)