The requirements of the visa depend upon the country from where the candidates are coming. If the candidates are coming from the countries belonging to the EU, there is no requirement of visas for such candidates.
If the candidates do not belong to the countries of the EU, they need to contact the embassy to know whether there is a requirement of a visa to migrate to Ireland. The candidates whose country does not have an Irish Diplomatic mission have to apply for a visa. They can download and fill the form before departing their home country.