If whoever said a C402 with the missus and 10 kids is legal was thinking 2 kids per seat, side by side, lap strap, 77kgs blah blah.. Then that may not be legal. Theres a table in the one of the C books that states maximum number of extra pax based on seats available.
As for the A380 thing, someone once said on here that an aviation lawyer in their spare time (lawyer, spare time.. free??) worked out that a PPL could fly an A380 legally, much the same way as a few people on here have said.. I don't recall reading a pax limit.