You may not see all the trainers on board because the number of trainers on board differs each day.
Monday - 4 people
Tuesday - 3 people
Wednesday - 4 people
Thursday - 5 people
Friday - 4 people
Saturday - 6 people
Sunday - 7 people
Check here for a list of Trainers that will be on board, and which Pokemon they own. Of course, head down to the Black 2 and White 2 section, and they will have different Pokemon with different levels depending on if you have finished the game or not.
Hope I helped. :)
Source: Above Link