a molly/guppie crossing is very rare, and if anyone does have, PLEASE post a pic, I'd love to see it.
Platys and swords are easyer, Thats how many of the colour ect of platties were done, but you got to make shore the females are virgins.
why would you want to cross anyway??
nothing wrong with crossing, but no one will realy want the fry. I have tryed crossing Black-chinned livebearers, with guppies, as no one knew if it could be done, never got any fry.