cr.B, st.C, st.D, and cr.D are all pretty useful as poking tools. st.C is probably the least useful due to how slow it is, but it's still better than some similar moves of other characters because it hits many crouching characters and is cancelable. st.D is nice for its lower body invincibility and faster startup than b+B. cr.D has pretty good range and startup and is also cancelable, so it's a good sweep overall. Remember that cancelable normals can cancel into command normals (b+B, b+D) or specials (qcb+X, b~f+P) even on whiff, so as long as you make use of this, you don't have to worry too much about being whiff-punished, especially with the extremely fast b+D available.