I baked a cake which is sweet and moist. I would like to make cake balls with it, but I wonder what should I use as frosting to not make it sweeter! Is it possible to ignore any kind of frosting and does coating the cake balls - which are made out of the cake only- work? I mean will it keep its shape that way? Any suggestions would be greatly appreciated.
Coating your cake balls is a good idea, it will help them retain their moisture and shape. There are plenty of not especially sweet options, I would try a cream cheese based frosting with less sugar or a medium-sweet chocolate ganache.
As another option, you can keep the sweetness down by using something that will give a very thin glaze, such as a thin royal icing. You can make it with just confectioner's sugar and water, but if you have meringue powder, it'll set up a bit firmer.
Pour it into a cup, dip the cake pops, then shake or twirl to remove most of it, then let dry. (a block of styrofoam, works well for drying things on sticks ... you can also use a corrugated carboad box (shorter than the height of the sticks), poke holes in the top, and then set them in that.
You'll have to play with the thickness of the glaze so you get a thin coat, but not so runny that it all drips off when drying. Twirling to remove excess is pretty important ... just hold the cake pop upside down in a large cup, then spin the stick between your fingers.
If the flavor is compatable with the cake, you can also help to balance out the extra sweetness by using lemon juice as some of the liquid.