Are you sure that the disc is for the correct region? If you have a US Wii U it needs to be a US copy of Pikmin 3.
Does your Wii U have the latest updates installed?
If you have access to another Wii U (perhaps a friend owns one), I would also try the disc in their system. If the disc doesn't work in another system, I would either contact the seller for a replacement (or a refund) or give Nintendo a call at 1-800-255-3700 to get further troubleshooting assistance.