Actually, all of those IP's are owned by Sony. Sucker Punch and Naughty Dog are internal Sony studios (so Sony owns IPs they make). Insomniac Games may be independent, but Sony owns the Ratchet & Clank IP (not Insomniac). So it's not that difficult. Sony is publishing the game too, so it's most likely that Sony asked them to make the game (Sony owns the IPs, so they didn't need permission from anyone).
So bottom line, Sony is publishing a game featuring all characters that they own.