Serena had a few sparked ideas. #1 chat.

Serena: So Ash... What will you do when you go home?

Ash: Hmmm... Don't know... Maybe I'll go visit my Pokemon at Professor Oaks Lab. I do have a lot after all and I'm pretty sure they miss me because I sure do!

Serena: Really? How much do you actually have?

Ash: Trust me I have a lot! *laughing*

Serena: *laughing*

Ash: They've been with me since I was traveling around in 5 different regions. They helped me learn some thing and I learned form them. This will help me as a trainer to be stronger and to aim for my goal!

Serena: Wow... You learn from your Pokemon... That's amazing!

Ash: Each piece of info will help me become a Pokemon master! I'm really determined to give it my all!

Serena: Wow Ash... *blushing* *gazing* Your so amazing!...

Ash: Huh?

Serena: *blushing* Eh! ... Let's keep going forward!

Serena was now too nervous to continue. Then she realized there was only 5 hours left. She had to make it last because she would never get this chance again to be alone with her crush.
Plan #2 try holding hands! (Again)

Serena was swinging her hand as she was walking. Then she tried to grab his hand. This time she failed (again) she got way too nervous but then she realized," Don't give up till its over! " This does apply. Right? So Serena tried again and did it, but then got too questioned from Ash.

Ash: Huh? Serena what's the matter?

Serena: Oh! I-I'm sorry! M-My hand is kinda cold....

Ash: Oh then here you want my gloves?

Serena: *blurts out* Yes!!

Ash: Okay! *doesn't notice why she blurts out* *gives her his gloves*

Serena: Thanks!

The only reason she said yes was because she was too nervous to hold his hands so she would rather have her hands inside the gloves he always wore.
But now she was down to her last plan.
Plan #3 share deep thoughts (just not how she's in love with him)

Serena: It's gonna be very sad when we all split up... I don't know what to do...

Ash: ....

Serena: But I do hope we'll see each other again though. I can't imagine not seeing eachother again....

Ash: Don't worry we definitely will!

Serena: I do wish you good luck.

Ash: Thanks!

Serena: Please do be careful out there...

Ash: Serena! Of course I will! *laughing*

Serena:... ....

Ash: Serena?

But now this topic was really getting to her. What will she do after this? Pokemon performances was 50/50 but she didn't want everyone to split up. She's gonna miss everyone. Especially Ash. Now she began to cry if the thought not seeing eachother again.

Ash: ! Serena! What's wrong?

Serena: *crying*

Ash: Serena! Please say something!

Serena: *sobbing* let's not separate! Let's all continue adventures together!!

Ash: *realizing* Serena.... *tearing up*