When the party (which, at this point consists of you, your partner, Virizion, Dunsparce, Emolga, Espeon, and Umbreon) gets ready to enter the Magnagate leading to the Great Glacier, as the gate closes, Dunsparce, who had been randomly chosen by straw-drawing to stay behind per one of HAPPI's rules, starts crying when he wishes good luck to the team. Suddenly, Emolga jumps out of the Magnagate and tosses Dunsparce into it, wishing him to have a great adventure with the others. What an excellent way to show what great friends Emolga and Dunsparce are.
Virizion, the Pokemon with the best reason to go to the Glacier Palace, offered to stay behind so Dunsparce could go. That's some real friendship.
After bringing you to a lake, your partner, Emolga, Dunsparce, Virizion, Umbreon, and Espeon each take turns treating your wounds while you are unconscious after you are knocked out due to Kyurem rapidly stomping on you. True friendship indeed.
When the Bittercold is weakening your character and seems impossible to defeat or damage, but your friends and team are all cheering you on and believing in you from afar, empowering you.
When the rest of the cast in the ending don't forget you.
Your character's return from the human world in the post mission.
While the ending past two PMD games were pure Tear Jerker, this game manages to be a Tear Jerkerand a heart warmer at the same time. Specifically, during the after party where the towns folk celerbrate you sucessfully beating the Bittercold and saving the world from destruction, Hydreigon confirms what the player character was worried of that, indeed, you will be forced to return to the human world now that the reason you were summoned was complete. This time around though, Hydreigon also informs you that the others will forget you while you fade away back to your world. When Hydreigon ask if you would want to say goodbye to them before you go sense you have until the next day before it happens, the player character sadly declines, figuring that if his partners were going to forget him anyways he might as well not cause them unnecessary grief, while Hydreigon promises to escort the player character as long as it can while you return to the human world.
The next day, the player character gets up early while making sure not to disturb his sleeping partner, he leaves and takes one last look at their house while remembering all the good times he had with his partner. With a heavy heart, he continues to reminisce while making his way up to the hill of Post Town, where Hydreigon asks him if he has any regrets before leaving. The player character says no, when really he was extremely disappointed in himself for not keeping the promise he made to his partner about staying in the Pokemon world with them even after the reason he was summoned was completed. With that, Hydreigon starts to escort him back to the human world while the player character is engulfed in a ball of light.
While the player character is ascending into the sky just like how he fell from it into the Pokemon world at the start of his adventure, he gets one last look at Paradise he and his partner created... When he notices all his partners had gathered in main hub and were looking up at him with a smile. At first, the player character is shocked, but quickly remembers what Hydreigon had said about them forgetting him, and figures that it wasn't him specifically they were looking at, but rather the ball of light ascending into the sky.
As the player character continues to ascend into the 'heavens', he gets one last look at the Rainbows of Hope he had restored by restoring everyones faith in each other and beating the Bittercold, Hydreigon tells him this is as far as he can go... And hands him a Frism. Specifically, his partners Frism.
As the player character activates it, a message from the partner starts to play. It is then revealed the partner realized early on that the player character would be forced to break their promise about staying with them in the Pokemon world, and harbors no ill feelings towards him, as he realized that the player character also has people in the human world who care about him, and says that he would send him off with a smile when he has to leave. He also says that he had confronted Hydreigon to get confirmation on this, and when he heard he would be forced to forget the player character, he said that there would be no way anyone could forget about him, and promises that he won't as the other towns folk also join in to say their goodbyes and promise the same. It is at this point the player character realizes they were looking at him, and were sending him off with a smile just as they had promised. It is at this point the player character finally breaks down and cries, just as the credits roll...
And then... After the credits...
Partner: Good-bye, (player character). No matter how great the distance between us... Even if we never meet again... Our hearts will always be together. I will always be with you in spirit. Forever and ever.The End
And in the post game, the player character ends up at the same pool from the intro, and the player character notices one thing; he'll never be able to return to the Pokemon world where his partner is. Then, although Hydreigon tells the player character that everyone will forget him, the townspeople refuse to forget him. The partner also says, "Everybody loved (player character)." Then, it cuts to the partner, who is controlled throughout the post game storyline. After the first day, Emolga and Dunsparce ask Hydreigon to explain how Hydreigon met the player character. Hours later, Hydreigon is talking about random things, while Emolga and Dunspace regret asking Hydreigon. Meanwhile, Keldeo is on a cliff when Virizion enters. Eventually, they talk for a while. Virizion even mentions that Keldeo is not her best friend... but Keldeo begins sobbing until Virizion calms down Keldeo, even stating that there is no best or 2nd best friend, and that Keldeo is a good friend to Virizion. (Though the reason Virizion was only kidding was because in her opinion, the way Keldeo reacts is hilarious.) And so, Keldeo and Virizion become friends once again.
After the second day, Hydreigon is relaxing on the cliffs when he hears something and comes up close to the screen. Dunsparce then asks Hydreigon on what was he doing, and Hydreigon, without giving an explanation, tells Dunsparce that there is a way the player character may come back.
Then, before the Worldcore, the partner encounters Emolga, who angrily tells the partner that Hydreigon forgot to pay the bills and flew off. After Hydreigon appears, he tells the partner and Emolga to come to the Cafe. While in the Cafe, Hydreigon tells everyone that the player character can come back in one possible way; the Worldcore. The partner, however, has to go to the Worldcore, while Hydreigon tells the partner that he will appear at the Hill of Universal Order. Once there, the partner must wish that the player character can travel between the human world and the Pokemon world at will. The partner then sets off to the Worldcore.
After the partner reaches the Hill of Universal Order, the partner comes across yet another cliffside. Hydreigon appears and tells the partner to make the wish. But the plan backfires, for the Hill of Universal Order is about to collapse. Hydreigon then tells the partner that the wish is just too much. The partner then comments that once it collapses, the partner will never be able to return until many years later. However, the player character had seen everything. Hydreigon then reveals that the player character was watching the partner all this time. Then, the partner then begs the player character to come back.
The player character is then put in a But Thou Must situation. If "Yes" is selected, the player character then yells that he wants to return to the Pokemon world. This saves the Hill of Universal Order from collapsing, and not only that, the player character returns in the ball of light. Once the ball of light dissolves, the partner rushes to the player character and hugs the player character. And after the cutscene, this ends the post game storyline.
The first thing that your partner says to you when you return to the Pokemon World...
Partner: Welcome home.
Leavanny being understanding when Espeon, wracked with guilt and broken down in tears, explains how she entrusted Swadloon with the Entercards, inadvertently putting him in as much danger as she was in. Espeon felt so terrible about doing this, she went back to Swadloon, but he was already gone, and she never stopped thinking and worrying about him as Purugly and Toxicroak pursued her.
In the same scene, Leavanny says how proud she is of her son for keeping his promise.
After your partner and you come back from Post Town (after telling everyone about the end of the world approaching), things are looking bleak...until Lillipup comes in and tell you that he still wants to live and doesn't want to give up because he doesn't want to lose his friend Swadloon or his grandfather. When you and your party leave your home, you find Lillipup's grandfather and Swadloon's mother (as well as Swadloon and Swanna) waiting outside. After apologizing for running away, they tell you that they're willing to help out towards your cause.
Partner: (to Lillipup) You want to know what you can do? Be brave! Have the courage to stand up and face whatever the future might bring you!