Here's the scene where the Rain begins, Then Emerl and his friends finds Charmander, Then a Trainer name Cross appears and heads to the cave in Team Robot in Pokemon Movie: I Choose You!.
(Then suddenly it began it rain)
Gmerl: Now what?
Ash Ketchum: Rain!
Verity: Just like that kid said!
Samurai Jack: Come on, Let's find the shelter.
(As the heroes runs to find the shelter from the rain)
Snowy: (Barks)
Tintin: What is it, Snowy?
(Then the Heroes stops and looked to See Charmander, who was sitting in the Rock, alone and very sad)
Ash Ketchum: A Charmander!
Emerl: A Fire-Type Pokemon.
Verity: It doesn't look like it's very happy.
Ashi: Maybe, Charmander's really sad now.
Sci-Twi: I wonder what's that poor Charmander doing here?
Ash Ketchum: Hey what are you doing out in the rain like this?
(Charmander sees something and runs to it's trainer and right next to him was a Lycanroc Midnight form)
Verity: That must be it's trainer.
Diddy Kong: Check out that Lycanroc.
Donkey Kong: A midnight form.
(Charmander hugs a trainer on it's leg, but he kicks it away much to our heroes' shock in horror)
Cross: Your still here? Go away!
Thomson: That wasn't very nice!
Dewie: What the heck is wrong with you!?
Verity: Hey, wait! Are you it's trainer?
Cross: Who's asking?
Ash Ketchum: Answer the question!
Cross: What are you worked up about? Yeah, orginally I was.
Ash Ketchum: Orginally?
SpongeBob Squarepants: What do you mean your orginally to Charmander?
Cross: I ditched the weakling. There Charmander like that all over the place. But then it just kept following me, so I told it to wait here.
Ash Ketchum: What an awful thing to say!
Gmerl: What's wrong with you!?
Samurai Jack: You can't abandon Charmander!
Verity: They're right! When you've caught a Pokemon and then you tell it to wait, some of them will actually wait forever!
Cross: So what's the problem?
Ash Ketchum: Hold it!
(Ash grabs Cross' right shoulder with his left hand and then Lycanroc [Midnight form] headbutted Ash to the ground)
Emerl: Ash!
Cross: Only a Pokemon's strength matters! If it's gonna survive it had better grow stronger!
Ash Ketchum: What!?
Verity: Wait, isn't it a trainer's job to help their make Pokemon strong?!
Cross: Nah... and what do you get for that work anyway?
Ash Ketchum: You get to become friends!
Cross: You're too soft. The only thing friendship does is make a Pokemon weak.
Patrick: If you don't apologize to Charmander and make it come back to you! Things are gonna get crazy!
Cross: Shut up, Pink-boy.
(Lycanroc Midnight form tackles Patrick)
SpongeBob Squarepants: Patrick!
Ed: Naughty trainer.
Cross: You too, monobrow imbecile!
(Lycanroc Midnight form tackles Ed)
Double-D: Who do you think you are!?
Cross: My name is Cross. I'm gonna become the greatest trainer ever.
Ash Ketchum: Hey! Hold it!
(Charmander tries to run to the trainer but collapses to the ground)
Ash Ketchum: Charmander!
Tintin: Oh no, it's getting weaker!
Verity: It's flame is getting weaker!
Professor Calculus: That's awful!
Verity: And if Charmander's flame goes out then...
Samurai Jack: It might die.
Verity: Everyone, We've got to do something!
Ash Ketchum: Right.
(Ash picks up the weak Charmander as the heroes to find shelter. The heroes finally made it to the cave and they saw Sorrel and Lucario sitting by the campfire)
Emerl: It's the boy and his Lucario again.
(Sorrel jumps off the rocks to see Charmander)
Sorrel: You left it out in the rain! What were you thinking!?
Verity: Calm down, it wasn't Ash's fault. It was in the rain after it's trainer abandonded it. It would've stayed out in the rain forever.
(Later)