My routes on three separate days will be Dublin to Tralee then Tralee to Galway then Galway back to Dublin. If I do not reserve seats for 2nd class, what do you think the chances of not having a seat? Thank you so much!!
I've bought tickets the day before or even day of for train travel during peak season (June-July-August) and never had a problem not finding a seat.
Sometimes when trains are crowded, they want you to put your luggage on the racks near the exit door so it's out of your sight. You may want to buy a simple cable lock if you are worried about your bag.
The only time you may have a problem is on a Friday evening on trains leaving Dublin or Sunday afternoon/evening on trains in to Dublin. They may be crowded but you will be able to find a seat.