Here's why:
* Water Pokemon Locations: Most Water Pokemon in Emerald are found in water. You can't use traditional capture methods like Poke Balls or other items to catch them in these areas.
* Fishing Mechanics: The game specifically designed the fishing mechanic to allow players to encounter Water Pokemon.
Here's a breakdown of the possibilities:
* Early Game: You can get a Mudkip (Water-type) as a starter Pokemon. This is the only Water Pokemon you can encounter without a fishing rod in the early stages of the game.
* Trades: You could trade with other players for Water Pokemon.
* Events: Some events in Emerald might offer Water Pokemon, but these are rare occurrences.
Getting a Fishing Rod
You can obtain the Old Rod from the Old Man in Slateport City after beating the first gym leader. This allows you to catch basic Water Pokemon. You can later obtain a Good Rod and a Super Rod for catching more powerful Water Pokemon.