Some people mean transitional fossils as 'half-cat, half-dog' sort of thing. This means that they probably do not understand evolution. Every fossil found is probably a transitional fossil...
Probably:
Some creationists say that you can't assume that whatever was fossilised had offspring. However, since fossilisation is rare, it can be assumed that the fossilised creature was part of a larger population of similar organisms. They would have bred also. It may not have been, but it probably was (as in, really probable, not just 75%).
So we assume that every fossil (until other evidence) is a transitional fossil.