Dear Vrushi,
Please let us know whether you get the order from Ind. Court declaring the strike as illegal. If yes, then whether the strike was withdrawn immediately within 24 hours, if yes, then it will not be illegal strike.
Only participating in illegal strike will not be amount to dismissal, which would be harsh punishment.
It need to club all the charges like indiscipline, disobeying legal orders of superior, threatening to co-employees, distroying / sabotage the property of company, etc.
You need to issue the chargesheet, conduct the domestic enquiry, observe priciple of natural justice.
Give chance to the concern employees to defend themselve, issue the enquiry report to them and second show cause notice.
Then based on direction of the Management you can issue dismissal order for the concerned employees.
Regards,
Avinash K.