Babies:
Fruity Plum - rapidfire weak shots (across 3 lanes?)
Twisted Pair - shoots forwards and backwards
Little brimstone - charge up a laser that hits whole lane
clot (special) - basic shooter that loses hp over time (can't die from that)
items:
holy mantle - placed babies block the first dmg they take
worm friend - grabs (stuns) enemies every so often
daddy long legs - stomps on and damages enemies every so often
little clot - you can drag directly from heart count to board and spawn a clot
quints - (non-imp) babies leave imps on death
Enemies:
real final boss - mom
Misc:
mark baby tags (like defensive and red and spike, for items/achievments)
item stacking (just increase effects for some items with multiple stacks like backpack, pill bag and salvation)
use pills on monsters (I know this has been suggested before)