First beat the final level. After the credits play your file and go to the second item shop. There will be a pig. Talk to it and it will ask a question. Say yes and all of the Mini Games will be Piggy themed. If you want to stop, simply go to the pig and say no.

For each course you clear you earn a vision orb. Once you beaten that course go back to it and beat it again. Successive successful course completion will earn you new frames.