I love garble and pinkie just because of the ship name, garblepie. There kids are crumble pie, vintage pie, strawberry rhubarb pie and sweet potato pie.
My idea for how pinkie and garble get together is basically, ember not wanting to go to fancy events, sends garble in her place, to f with him. Pinkie would be helping twilight with planning the events but not really fitting in with the fancy. Pinkie and Garble would start hanging both feeling out of place.