Team Dimensional’s goal is to reunite the old Gods of the Sinnoh region with our world, and to that end they are seeking to capture nearly every legendary in the region. First and foremost, they need to capture the Lake Trio, Azelf, Uxie and Mesprit.
You will have encountered Team Dimensional at many steps along your journey, as they can be found in nearly every town, either proselytizing to the masses or researching ancient legends. However, it is not until you pass by the entrance to Lake Valor, where Dimensional grunts will block your way, that it becomes clear that Team Dimensional are up to something. This is made even clearer by talking to Aroma Specialist Mars, Lady Jupiter, and Ace Trainer Saturn, but it does the details of Team Dimensional’s operation do not come to light until after you have defeated Keira at the Hearthome city gym.
You will once again meet Dawn as you are leaving Hearthome, and she will congratulate you on your progress. However, she will receive a call from Assistant Professor Larch demanding she come to Lake Verity immediately.
You and Dawn speed to the Verity Lakefront, where Acolyte Spacia is attempting to capture the lake’s legendary Pokémon, Mesprit. However, Spacia is unable to successfully catch the Pokémon, and orders some grunts to capture it by means other than a Pokéball. Upon hearing this, Mesprit flees. Specifically, the emotion Pokémon flees to you, the player, and unless there is an open space in your party you will be prompted to send a member of your team to a box. Mesprit will join your team, whether you like it or not.
Spacia and the grunts challenge you in an attempt to steal Mesprit from you, but Dawn and Lucas easily defeat the grunts while you take on Spacia. Once defeated, Spacia has no choice but to retreat.
This development sends you to Canalave town, where, once Roark’s Gym is defeated, your rivals and Assistant Professor Larch study up on the guardians of the lakes. It’s clear that Team Dimensional want to get their hands on these Pokémon, likely as a means to summon Dialga Palkia, and perhaps Giratina.
In hopes of preventing Team Dimensional from capturing any other lake Pokémon, you meet one of your rivals, Matilda at Lake Valor. There you will find Acolyte Tempus and three grunts restraining Azelf, the willpower Pokémon. Tempus is determined to succeed where Spacia failed. However, when two of the grunts challenge the player and Matilda to a double battle in hopes of driving you off, Azelf is able to break free, and becomes a part of Matilda’s Pokémon team. You and Matilda continue to battle as a team against Tempus and the remaining grunt, and once again emerge victorious.
The last lake, Lake Acuity, is reached after you have made it to Snowpoint city. You have time to reach the Pokémon center there before Cato appears, telling you something is wrong at the lakefront. At lake Acuity, you and Cato battle a group of grunts guarding the lakefront before surfing to the cave in the center of the lake. There you must face Pravita, who plans to defeat you and capture Uxie for herself. Cato isn’t confident enough to face her alone, and you battle as a team against her, which she insists is unfair. Even after being defeated, she throws one last Pokéball at the knowledge Pokémon, but it escapes from the ball and situates itself in Cato’s party.
After you defeat Candice at Snowpoint gym, Dawn meets up with you again, and is encouraged by the possibility that Team Dimensional will be stopped in their tracks now that they can no longer bring together the Lake Trio and get a hold of the red chain.
However, just before you reach Sunyshore city to challenge the final gym, an earthquake rattles the region. Barry, Sunyshore’s gym leader, runs headlong into you, and hurriedly explains what’s going on:
Something big is happening in turnback cave, off of route 214, and you’re that kid Dawn’s been talking to, right? He tells you to go ahead and check it out while he goes to find Dawn.
When you reach sendoff spring, where the cave’s entrance is located (and the path to which you could SWEAR wasn’t there yesterday…), Matilda is already there. She explains that she was on route 214 when the ground shook, and decided to head towards where the shake might’ve come from. She also called Cato and told him what was going on. The pair of you climb down to the cave entrance, and just before you head in Cato rushes down into the spring to join you.
The path into the heart of the cave, which is labyrinthine at the best of times, is lined by Team Dimensional grunts. You, Matilda, and Cato fight your way through them until you reach Giratina’s chamber, where the renegade Pokémon is looming over Acolyte Pravita and Themis, Team Dimensional’s leader.
Themis reveals to you that he has summoned Giratina, and will use this newfound power to bring forward Dialga and Palkia as well. And, all the better, the three of you are now here, so Team Dimensional has been able to bring the lake trio together after all!
In an attempt to stop Themis, you challenge him to a battle. Pravita takes on both Cato and Matilda while you face Themis, and his team: Rampardos, Bastiodon, Dustox, Clefable, and Toxicroak. Though he is upset that you defeat him, he is not swayed, and turns his attention Giratina instead.
Finally,Barry has returned with Dawn and Lucas, but it may already be too late. Themis calls upon Giratina’s power, and a dark portal opens in the center of the room. Themis, Pravita, the player, Matilda, and Cato are all pulled briefly through the distortion world only to be spat out onto the peak of Mt. Coronet at the spear pillars.
Tempus and Spatia are waiting at the pillars, and are glad to see that their leader has succeeded. With Giratina’s power, Themis calls forth Dialga and Palkia, and the whole region, perhaps the whole of reality, shakes under the strain.
Themis asks the great legendaries how Team Dimensional can serve them, but Sinnoh’s creators have only rage. Another portal to the distortion world opens in an attempt to balance all of this power, but Giratina is weakened from being restrained and controlled by Themis. Even as the mountain and the ruins begin to crumble under the pressure, Themis persists. This, he is convinced, is the will of these gods. They will reshape Sinnoh to their liking! Even if it means the destruction of everything we know and hold dear. Time and space are being torn asunder by Dialga and Palkia, and Giratina is exerting more and more power in a vain attempt to compensate. Everything is threatening to shake apart at an atomic level! It would hardly be possible to contain all three of these powerful, legendary Pokémon at all, and truly impossible to contain them quickly enough to end this destruction. They cannot return to a state of balance now that they have been summoned; their anger will not allow them, and with time, space, and distortion all in one place, to remove one would surely tip the scales into utter, world ending chaos!
The shuddering cacophony of inter-dimensional distress reaches an overwhelming fever-pitch, before being abruptly stilled.
Arceus stands before you, looking down upon the scene. All is silent. Dialga, Palkia, and Giratina turn toward it. In a flash, each of the other legendaries is returned to their rightful places.
Arceus turns its attention to Themis.
Themis bows down before Arceus, and his acolytes follow suit. He swears devotion to Arceus, and offers the Pokémon anything it could want. He asks that it remold Sinnoh to its liking, and take Team Dimensional as its servants. After a moment of hesitation [… … …], Arceus gives its answer:
No.
In a blink, Themis is gone, teleported elsewhere just like Dialga, Palkia, and Giratina. The acolytes recoil in horror, and everyone is unsure what to do. No one among you would be brave or idiotic enough to face the Alpha Pokémon.
…Right?
Wrong. You’re a player character, likely armed with a master ball, and you’ve been looking forward to just such an opportunity like this. It’s time to save your game, and face the legendary Arceus. Ideally, you will catch Arceus here, but if you defeat it instead you can return to the spear pillar after defeating the champion and obtaining all of the different type plates available in the Sinnoh region, at which point Arceus will re-spawn and you can try again.
With Arceus caught, reality has returned to a stable state, and the former acolytes of Team Dimensional are absolutely terrified of you. Tempus offers you the role of the team’s leader, but even if you don’t refuse, Pravita rejects the idea. Though none of them have given up their ideals and goals of a better, more advanced world, Spatia reasons that without their determined, charismatic leader, Team Dimensional will surely disband.
Now that Team Dimensional and their tampering with the legendary Pokémon has been stopped, you can finish your gym challenge in peace, and face the elite four and champion.
It isn’t until the post-game that you will find out that Themis has been discovered, alive and well, in Floaroma town. You can go meet him there and discover that his memory is hazy at best, losing focus soon after he became a Team Galactic grunt. Aroma specialist Mars is working to get him re-situated. He’s considering becoming a rancher!
