...you are basically forced to get an already hard to obtain Ditto (unless you get someone to help you or reach Champion first for the free Ditto) and mass breed a ton of Unowns, at least FOURTEEN OF THEM to be precise...
you dont need ditto to breed unown.... you can breed unowns with each other. theres a whole forumla.
here is a tool you can use to determine which unown letters will produce what. theres only 4 pumpkaboo sizes but theres what, 28 unown formes? it would be ridiculous to have a 1/28 chance of hatching the forme you want from one egg so thats why they're all separate. anyways i dont mean this to invalidate your complaints or anything, i mostly wanted to point out the calculator i linked cause i think a lot of people dont really know about it.