In this game, you play as a rookie Ranger in the land of Fiore, under the Ring Town Leader Hayate. Other Ranger Leaders include Joe from Fall City, Kamuri from Summerland, and Erida from Wint Town, all of which serve under the Ranger Union where Prof. Shinbara is the top technical consultant, and is actually the person who invented the Capture Styler. There is a rather fixed set of missions for you to go on, which you clear in order to increase your Ranger Rank level. The Ranger Rank level, as described above, unlocks the avalability of certain types of Pokémon Assist, increases the number of wild Pokémon you can bring, and also raises the energy cage numbers of your partner. Your partner will be Minun if you pick the male Ranger, and Plusle for the female Ranger. Either way, the opposite gender Ranger will be your companion on and off in the game, and many a times, the two of you will go on missions together.
In the land of Fiore, you capture Pokémon with the help of a device known as the Capture Styler (together with the Capture Disc) instead of pokeballs. The Styler has an HP bar, shown at the top of the screen, and you will have to start from your previous save point again if it gets reduced to zero. Click Here for further info Wild Pokémon in Ranger stay in a rather fixed area in their habitat, which means if you find a Pikachu near the entrance of the Lila Forest, it will always be there, unless you have captured it and are taking it along with you of course. But after you have used Pikachu and it departs, you go back to where you found it, it will still be there. So, it's really not that big a trouble to find Pokémon you need, because they won't migrate to another spot. So what do you do with the captured Pokémon? Well, there are various obstacles along your way in the missions which require certain abilites to clear, and to use a Pokémon's ability, you have to capture it and put it in your team first. Another reason for capturing Pokémon is to use it during Pokémon Assist for capturing tougher Pokémon. Both kinds of usage will set free the Pokémon afterwards, but as said above, the Pokémon will simply return to where you found it. At the beginning, you can only bring 4 wild Pokémon with you, but as your Ranger Rank increases, you will be able to bring a maximum of 7. However, until the credits roll, you will be forced to release all the Pokémon once you exit that particular region, as you are not allowed to bring Pokémon outside the habitats according to the Ranger regulations.
The villain of the game is Team Go-Go headed by Ragou, who is actually an old colleague of Prof. Shinbara who got jealous of the professor's fame. Team Go-Go stole a newly devloped Super Styler from Prof. Shinbara at the beginning of the game, and developed their own Power Styler from the model. Ragou used it to capture the legendary beasts Entei, Raikou, and Suicune, and you must free them. Throughout the game, you will be confronted by various Team Go-Go admins and members, which unleash their Pokémon at you. To beat them, you simply capture their Pokémon with your Styler, and set them free afterwards. After you have beaten Ragou and freed the beasts, some Team Go-Go remnants will stir up the legendary titans Kyogre, Groudon and Rayquaza, which serve as extra missions after the end credits roll. The full completion of the game comes after you have completed the Ranger Browser of 210 Pokémon. When you have done so, you will see a special animation at the Ring Town Ranger Base where everyone you know come to congratulate you, and Hayate rewards you with the Completion Emblem.