The principle of monocolor teams is to make your damage more reliable - that way, you only need to expect one type of orbs to troll, not a bunch.
To help with this, monocolor teams tend to make heavy usage of orb changers to manipulate the board, for example, my Monored team uses both Gigas The Great (Turns Heart Cubes into Fire Orbs) and Meteor Volcano Dragon (Turns Dark Orbs into Fire Orbs) to help with that.
In general, if the orbs don't drop, you try to clear as many orbs as possible in a single go, to increase the chances of the orbs you want dropping, if the opponent resists your element, you essentially cry in a corner and try to do as much damage as possible while having to deal with the permanent x0,5 multiplier.
I'm not too familiar with Healer teams myself, the only blue healer I'm aware of would be Siren and blue Valkyrie, however you can already do some good control with these two, as Siren turns red orbs into hearts, and then blue Valkyrie turns these hearts into water. Controlling three out of the six colors on the board (Fire, Hearts and Water) already makes a monocolor team's job much easier, though admittedly, the more colors you control, the better, and if you have a way to turn all colors on the board into a single color and further enhance them, all the better (Though I'm not aware of any Water-Enhancers)
