For this theme you should definitely have yellow and blue color scheme in the decor
for foods you can use bananas, because the minions love bananas!, you can also use yellow and blue foods and any other food you can relate to the movie and theme
for party favors you can use swim goggles like the minions iconic goggles,
there are many ways you can make the cake, you can put figures of them on a cake, and for inspiration you can turn to pinterest
you can play the movie or project it at night for a fun summer party/ fall/ and spring
you can use google eyes, and markers and for the body you can use toilet paper tubes, paper towel tubes, and wrapping paper tubes, you can also use tape or glue to put them together, this can make a cute decoration or activity for the kids
i hope these ideas were helpful!, happy holidays and have fun party planning!