For Sapphire and Emerald Players, this is one of the first Version exclusive Pokémon that you will encounter, with its counterpart being Seedot in Ruby. This little guy is a Grass/Water type, a rare combination, that protects against some of its weaknesses. It also comes with Astonish, a ghost move that can hit anyone... except normal and dark types, so don't bother trying to hit Poochyena or Zigzagoon with it... you'll go nowhere. its not very useful now, but its ultimate form, Ludicolo is quite useful, so it's up to you if you want it now or later.
Now this guy is worth watching out for! Being Psychic, he's open to a powerful array of moves, that will require training to get. he's on all 3 versions, so nobody's left out of his abilities. Ralts is about as rare as Surskit, but is easier to capture, since he only knows growl when you find him. If anything, stay behind to catch him, because he's not only very rare, but he's only found on this route. But catching him is worth it, because of the moves that Ralts can get are powerful, and are further enhanced with good stats from its fully evolved form,Gardevoir. Small, but powerful.
#273 Seedot
#283 Surskit
This Guy is Exclusive to Ruby and Emerald, although, he's incredibly rare in Emerald. This guy is an example of passive battling, where he doesn't directly attack, but can still cause damage. He can do this with bide, a useful attack that attacks your foe with double the damage you recieved. Its main use in the late game is where its evolved form, Nuzleaf gets a powerful Psychic attack unique to it called Extrasensory! So, like Lotad, its use is made better later in the game.
This bug is incredibly rare on all versions, and so rare in emerald that you can only find them in swarms after you beat the game! But it probably isn't worth all the effort to get them now, so save them for later in the game. However, it is best advised, due to their high rarity, that you catch the first one you see, so you can spare yourself hours searching for it, even if finding one now isn't on your mind. They are Bug/Water Combo, with an interesting array of moves when trained high levels, and with a different moveset when evolved, selective evolving can make it a quite useful Pokémon later in the game.
Ralts
Poochyena
Zigzagoon
Lotad
Seedot
Surskit
Wurmple
Marill
Goldeen
Magikarp
Corphish
