Chomi Prag, a Wisconsin attorney, will appear on the New Hampshire primary and has challenged Cruz’s eligibility to be president. If the person has to be running to challenge Cruz, Ms Prag is running, therefore should have standing
In his briefs, Cruz argues standing when it is appropriate (but it isn't, here), and also argues that the court lacks jurisdiction, and that the issue is not ripe.
On the question of jurisdiction, Cruz argues that only the electoral college and Congress have the power to decide questions of eligibility (so, a state is required to put all applicants on the ballot?), and that until the general election has been decided, it is premature to even ask the question (not ripe).
For the most part, courts don't want to be in the middle of a public controversy, so they dismiss the cases. But some DEM judge is going to make himself into a hero by finding Cruz to be unqualified, and ordering a Sec. of State to take his name off the ballot.