Its not possible. They're not close to being related. Now their is a hybrid between a Budgett's frog and a Cranwelli called a Chacophrys Pierottii. They clame its a natural hybrid that occurs, but I don't completely believe them.. They're both diploid, but one is Lepidobatrachus Laevis and the other Ceratophrys Cranwelli. Not the same species and don't look even similar.