Slowpoke asks Pikachu to play Chase. When Pikachu says yes, Slowpoke proceeds to run walk slowly away... By the time you can tackle him, he barely moves five feet away from you. You get the same thing from Caterpie.
Five feet? Caterpie is pretty much in the same place when the count-down starts and ends.
When you play Hide-and-Seek with Psyduck, he's usually just sitting out in the open.
Magikarp in Venusaur's Vine Swing attraction. The determination on his face as he's hanging from the vine, PLUS his landing expression caused many people to crack up.
Magikarp in Bulbasaur's Daring Dash. The most hardcore thing you will ever experience in the game.
Magikarp in the actual game's refined, cultured manner of speaking.
Just the fact that Magikarp participates in three of the attractions in the game, and the swimming one is not one of them.
Meowth's quiz game in the Cavern Zone.
Question 1: Was there a hot spring here when you got here? 1: Yes, 2: No, 3: I don't know
Question 2: Can Dugtrio fly? 1: Yes, 2: No, 3: I don't know
Question 3: What comes out of Bonsly's eyes? 1: Water, 2: Rainbows, 3: Fire
Murkrow bragging about how fast he is, only to be as fast as Caterpie when you play with him.
After you beat him, he says something to the effect of "Yeah, I probably should've just flown."
In the same vein as Meowth above, Corsola's quiz game in the Beach Zone.
Question 1: What does your tail look like? 1: Nothing, 2: The Moon, 3: A Lightning Bolt
The absurd cheapness of the Legendaries when they're playable is actually pretty funny.
Whenever bystanders become involved in a battle, the situation is likely to become this. Special points go to whenever the bystander defeats the opposing Pokémon for you.
There are some Idle Animations that play when standing in certain zones or standing near certain Pokémon that are worth a few laughs.
Beach Zone: Fans himself.
Lava Zone: Puts his ears down and makes a DX face.
Iceberg Zone: Shivers.
Haunted Zone: Cowers in fear.
Mr. Mime: Mimes by putting his hands on the "walls" of a "box" and then pulls a "rope" and goes "Pika!"
Feraligator: Roars at the player.
Driftblim: Spins around a few times and then jumps flapping his arms; trying to fly.
If you let (and I do mean LET) Caterpie win, he'll say "Hey I won! What do you know, don't judge a book by it's cover!"
Primape: I mean look at me! I know Iron Tail, and I don't even have a tail!
When you find Jirachi after inputting his code, when you talk to him, he says:
Just the fact that Oshawott uses his scalchop as a pillow when he sleeps. It may not look comfortable, but at least he's resourceful.
After the postgame, you can battle and befriend the Gothita, Gothorita and Gothitelle that have been working against you during the game. Talking to Gothorita afterward reveals that, unlike the other two, he's a male.