Ok, because there is so much info, I will post the post from Coronis on the serebiiforums:
Quoted from Coronis on serebiiforums:
1) Regigigas was indeed the 'surprise' Platinum saw into her bagpack. It 'entered' Platinum's empty Pokeball inside the Snowpoint Temple and tagged along with her to the final battleground. She passed it onto Dia much like how she did with Mamoswine. It managed to halt the clash between Dialga and Palkia with its massive strength to prevent Dia and his Mamoswine to get engulfed into the energy center created by Dialga and Palkia. Somehow Dr. Footstep has made a comment about Regigigas that 'It has been waiting for this time to lend its strength for Sinnoh together with a trainer'. I suppose the idea could be similar to how Celebi tagged along Ruby for the Groudon/Kyogre clash.
2) Platinum's Cherrim is confirmed to be from Gardenia, evolved from her Cherubi. Pachirisu also originated from Volkner, and he gave it to Maylene during their training to pass it on to Platinum. Froslass we already know it's from Candice.
3) Although Cyrus believes that the energy center created by the clash of Dialga and Palkia is the 'new universe' he dreams of, Charon secretly knows that it is in fact just the Distortion World's opening. He has some sort of 'meter' to monitor the dimensions. It is said that Byron managed to snatch it away from Charon, but in the process, Giratina appears from the Distortion World and drags Dialga, Palkia and Cyrus into the Distortion World.
4) It is confirmed that the 'two important people' Platinum tried to save in the Platinum arc are her original bodyguards which fate she learnt of at the end of the DP chapter. Dia and Pearl, on the other hand, managed to snatch some memo about a legendary Pokemon from Charon, and their task in the Platinum chapter seems to be investigating upon this.
5) Saque, as you can see from the scans in the previous post, is indeed a secret agent for Team Galactic. It was explained that a few year's back, when Cyrus started to plan for his 'new universe' scheme, he passed down orders to investigate on Pokemon who are related to space (Mars named Lunatone, Clefairy, and the other 'celestial' ones). Saque worked undercover in Team Rocket pretending to help Giovanni, but her true aim was to obtain Deoxys since it was exactly the Pokemon from space. She indeed owns a Darkrai, and it was in fact the 'unseen' Pokemon she attempted to use to recapture Deoxys at the end of FRLG, whose clash with Mewtwo caused the petrification of the 5 Dex Holders. After the FRLG events, Saque went off in search of the two Deoxys, and also to discover the mechanism behind how the petrification happened. It was also mentioned that Mewtwo was not affected in the process, and it tried to chase after Saque after the battle but did not manage to track her down.
6) The cloaked Galactic grunt is in fact a brainwashed grunt working for Saque. It wasn't really explained why he (or Saque) outted Team Galactic's plan to Platinum, but it seems like after her defeat by the Dex Holders in FRLG, Saque became obsessed with the Pokedex, and that's why this cloaked grunt snatched the Dexes of Dia, Pearl and Platinum. His current whereabouts are not explained. But an interesting fact is the the video-camera-flyer thing that this grunt used to spy on Dia on Iron Island, was said to have an 'evil' aura by Riley. This was in fact Saque's aura.
7) It turns out that Prof. Yanase from the Emerald series (the woman who was experimented on the Green Orb) was Platinum's mother. At the end of the DP series, she was the one who suggested Platinum to investigate upon the Distortion World. She also contacted Looker to assist Platinum, where Looker was working undercover in Team Galactic as a Scientist at the end, and it is said that he owns a Croagunk like in the games.
8) All the Team Galactic Commanders have left the scene at the end of the DP chapter and are scheming to 'resurface'.
9) When Riley visited Palmer at the Frontier, he told him about Hoenn's Frontier, and also gave him the broken video-camera-flyer to investigate, which Palmer passed to Thorton the machine-freak to work on
tldr;
Commentary time.
1.) Platinum did catch regigigas (even though it seems like another a$$-pull, just like Celebi from the R/S arc. :/
2.) Platinum DID get the rest of her team from the GymLeaders (I don't know why, but I guess they like her, and Volkner is too manly for a Pachirisu yo.)
3.) Charon is a manipulative jerk and tricked Cyrus into thinking that the distortion portal was the "new universe." But lol Dialga and Palkia need to be rescued.
4.) Whoever guessed that the bodyguard were the people who she needed to rescue: you guys win 10000 pennies for guessing right! /confetti Also, Dia and Pearl apparently now have the task to investigate Charon's memo on Legendary Pokemon. YAY THEY STILL HAVE A ROLE BESIDES BEING A PLOT DEVICE~
5.) Saque (Sird's Japanese name). Oh boy...Well.....Darkrai...that was unexpected..and the thing with the Team Galactic grunt was also unexpected, but YAY MEWTWO LIIIIIIIIIIIIIIIIVES >:U. ;3; Also, what are you up to, you evil lady you.. ;3; ? *shakes with anticipation*
6.) *points to 6* just.. D: my mind is still recovering guys. @@;;;
7.) ok more mind screw. That random Professor that was working on the Green Orb, Professor Yanase (btw ChuangYi, you fail for not giving her a dub name! :C) turns out to be Platinum's mother. ....D: WHAT THE FRICK?! D: But at least we have another Dex Holder with both parents, or at least a family, unlike some dex holders (that's right Red, I'm talking to you! :c )
8. ) Dun dun dun, the commanders will return.
9.)ONTO THE PLATINUM ARC! *point*
Also, this was not mentioned, but Bebe (Sinnoh's PC manager) and Hayley (the NPC from My Pokemon Ranch) appear in the story.
Unfortunately, we don't have info on the platinum arc's start yet (The DP arc officially ends in chapter 416, but the volume doesn't end until 422, which means we do not have info on those last few chapters.)
