On the way to Solaceon Town, Ash and friends arrive at the site of an unfinished bridge. They meet the builder, Isis, as well as the engineer and the nearby town mayor. The bridge needs to be completed in three days, but the Pokemon that cuts the stone, Bibarel, is not working. No matter what they try it just lounges around. Brock decides to help Isis, but because Bibarel won't work, they can't get the right size of the brick. The engineer then returns to the site and decides to use force to get Bibarel to work.
The heroes continue the journey and spot a bridge, though it is under construction. The heroes spot some workers, making Brock to go there as there is a woman, but sees the other two men yell at her, making her go at the end of the bridge. Brock goes to save her, but almost falls, as the Croagunk gets his hand. Brock is being told they were just discussing the construction of the bridge, nothing else. The head construction worker demands that she finishes the bridge in three days and leaves with the mayor.
The woman is Isis, so the heroes introduce themselves. The heroes offer help to finish the bridge. Isis knows that the mountain pass was the only was to continue towards other cities, so the bridge was in construction to connect the places. There was a famous stone-cutter, but he got his back injured and Isis was put in charge to finish. Isis does not know how to continue, so Brock gives the Machamp and Machoke his own food. Isis thanks Brock, but they are not the problem - the problem are the ones that have to cut stones. Team Rocket see this and think they will get a new base constructed, while Meowth knows with these Pokémon the boss would be pleased to have an entire castle for himself. Isis points at the stone-cutting worker - a Bibarel. Brock makes a new food to get it new energy to work. Bibarel eats the food, but goes back to sleeping.
Isis confesses she taught Bibarel how to cut stones - she is a breeder. She remembers she trained Bibarel and the master stonecutter came and got Bibarel for cutting stones elsewhere. When Isis came to him, she saw Bibarel was doing great, but when the master stonecutter left, Bibarel stopped working. Brock proposes that he could cut the stones, but Isis tells him it needs perfect dimensions. Brock wants to use Ash's Chimchar, Buizel and Turtwig, so Ash sends them, while Brock his Sudowoodo and Piplup joins them. Chimchar burns a stone with Flamethrower, while Buizel uses Water Gun to cool it down. Turtwig uses Razor Leaf and Sudowoodo does the same using Mimic. The stone falls and is polished, having quite good dimensions. With some calculations, Isis denies and tells the blocks do not have good dimensions. Brock wants to go again, but Bibarel comes and is not here to work, but to prevent it.
The heroes hear Machoke and Machamp - Team Rocket took them. Team Rocket got Bibarel, so Chimchar uses Flamethrower and Buizel Water Gun on robot arm, then Sudowoodo copies Turtwig's Razor Leaf and strikes, but there is no damage. Bibarel is angry and goes to chew on the iron bars. However, with a stronger chew, Bibarel destroys the bar, letting everyone out and leaving Pikachu to blast Team Rocket off. Everyone compliments them and Brock proposes some stonecutting, but Bibarel does not want to. The head engineer comes and sends Rhyhorn to do the task himself. Brock and Isis warn him if cut wrong, the bridge will not be completed, but the engineer ignores them, as Rhydon uses Horn Drill to cut. Bibarel strikes Rhydon, but gets hit in retaliation.
Rhydon goes to stomp on it, but gets bitten. The head engineer sends Magmar, Aggron and Metang. Aggron uses Iron Head, but misses. Metang uses Metal Claw, but Bibarel evades, but gets his by Magmar's Flamethrower. Bibarel still stands, wanting to protect the quarry, though the engineer sends his Pokémon to attack. Pikachu uses Iron Tail and hits Rhydon. Chimchar uses Flamethrower, Buizel Water Gun, Turtwig Razor Leaf, Sudowoodo Mimic to copy Razor Leaf and Piplup Bubblebeam. The engineer's Pokémon are easily defeated. The engineer charges using his machine, but falls down as the Machamp, with master stonecutter on his shoulder, came back. The stonecutter looked upon the blueprint and it was not correct. The blueprint required less stones, so he built a model to see what it should look like. Because of this, it would collapse easily.
Everyone is disgusted by the head engineer. With all the Pokémon here to threat, the man runs away. The stonecutter made a new blueprint, which should work. Everyone helps with the bridge construction and manage to build it in time. Isis is a bit embarrassed how she couldn't know what was Bibarel feeling, but Brock and the stonecutter think she, with time, will become a better breeder. The man gives them his own bands. Before they go, Brock flirts with Isis and gets jabbed.
This episode's name is a reference to statement "Grandma knows best".