Question

It's status move, so why it cannot hit Ground-types?

Answer 1

Immunity is based on the moves type, not damaging vs. non damaging moves. The same reason Toxic has no effect on Steel types, as they are immune to poison (the type, not the condition.)

Comments

But Confuse Ray can hit Normal-types, cannot it?

---

That is true, but remember that confusion is a secondary status effect, and thunder wave and toxic are main status effects (they show an icon when your pokemon has it.) secondary status effects are fair game for hitting types, like you can use attract on a ghost type despite it being normal.

---

Also, give people a chance to explain before voting them down. :/

---

I was waiting, NOW I will vote upXPP

---

Weird, I was just going to ask this question.