My 2 favorite cartoons stress friendship. My Little Pony: Friendship is Magic constantly shows how friendship is important. The series centers around 6 main (or mane!) characters. Usually one of them has a problem and refuses to get help which makes the problem worse. The other friends finally help and the original friend writes to the pony queen about the lesson.
The other cartoon is Winnie-the-Pooh. His best friend is Piglet who never turns Pooh away when he wants honey. Roo befriends a Hefflelump (elephant) in one of the movies. Pooh and the gang throw Tigger a party dressed like Tigger when it comes to light that he doesn't have a family.
International Friendship Day has several dates: July 30, Aug 2 or the 1st Sunday in Aug.