How long does it take for the boat to reach Kanto on your first trip? Do you have to do anything in paticular?
Actually, on your first trip, apart from battling all the trainers, you need to help a gentleman look for his little girl.
BTW, on your future trips on S.S. Aqua, you just need to sleep in your room. Battling all trainers is no longer necessary, but it's worth the experience.