Most of the cloth characters and dolls work best with stretch fabrics. Each set of instructions tells you the suggested fabrics for that project. For 5 skin tones of cotton stretch knit, I love the fabric at A Child’s Dream.  I have also used stretchy tank tops successfully for doll skin.    For the body and clothing, you can use any stretch fabric for poseable dolls.  Try it with upcycled clothing!  And if posing characters is not important to you, then any fabric can be used if your machine can stitch through it and you can turn it inside out. But be aware – stretch knits are easier to turn inside-out and they won’t fray like a woven fabric.