Dodgy Boss

Hey team was wondering if there was anything I could do about an employee who breaks a lot of employment laws. Employer only pays the 8% holiday pay and nothing else. No Annual, public holiday, sick leave, kiwi saver etc. All workers have been working for at least a year and some many years. No employee, past or present has had an employment contract. Employer is a pretty decent bloke but obviously breaks a lot of laws to save a bit of coin. Only reason everyone sticks around is because the group of lads who worker together get along really well. Was seeking some advice on how to maybe bring this up or handle this. Yes leaving is an option but I want to make sure when I do, the other workers are getting treated right.