* The Rival is not on the S.S. Anne. Your rival will appear later in the game, after you obtain your first gym badge.
* You don't battle anyone on the S.S. Anne. The S.S. Anne is primarily a location for story progression and item collecting, not for battles.
If you're looking to battle your rival, you'll need to progress through the game and encounter him at one of the following points:
* After your first gym badge: Your rival will challenge you on the route after the first gym.
* After your third gym badge: Your rival will challenge you in the Viridian City Gym.
* Before the Elite Four: You will have a final showdown with your rival before entering the Indigo Plateau.
Remember, the rival's team will be different based on the specific point in the game where you encounter him.