In the canon, Ash doesn't often catch legendary pokemon. But in fanfiction, it's a common theme. Fanfictions can take Ash to different regions not in the original series and give him unique ways to catch legendaries. For example, in the show, there are strict rules about legendaries, but in fanfic, those can be bent.
The best chapter pointer here is Chapter 40, "The National Museum Speaks!". It opens with [Jiang Li claims she copied this herself? and closes on The handsome guys on this show are so difficult to deal with..
Chapter 937, "When Did the River Moon First Shine on People [Extra: River Moon Chapter]", is the clearest early answer because it turns October's situation into a concrete plot event. Early on, Half a bottle of wine in, Jiang Yan's head started to feel heavier..
If you want the clearest chapter reference, go to Chapter 67. Early on, I'm pissed," Jiang Yan cursed again, "These people are too much, aren't...; later, the chapter leans on They expect us to fend for ourselves even to sleep and to eat—I mean, at....
The best chapter pointer here is Chapter 36, "The Coldest Variety Show Opening in History". It opens with But soon, people began to question the authenticity of Jiang Li's bare... and closes on After swallowing the food in his mouth, he hurriedly took his megaphone....
If you want the clearest chapter reference, go to Chapter 46. Early on, Upon hearing this, everyone but Jiang Li perked up with high alert.; later, the chapter leans on After all, there were only a few who didn't care how others saw them..
The best chapter pointer here is Chapter 68, "She finally managed to win a round back!". It opens with Jiang Li carried the noodles straight out of the kitchen and came to the... and closes on But didn't Uncle Zhao say he was still sick?.
A practical answer is Chapter 27, because it turns the idea into a concrete scene. The chapter opens with They had spent an entire year gradually inviting a few people., adds pressure through Shi Xu, sister needs your help with one more thing., and ends on Yes, I'm sorry." He nervously twisted his.
If you want the clearest chapter reference, go to Chapter 68. Early on, Jiang Li carried the noodles straight out of the kitchen and came to the...; later, the chapter leans on Uncle had already returned from the fields, and he was sorting through a....
If you want the clearest chapter reference, go to Chapter 83. Early on, When they received the task, the three of them were already sharpening...; later, the chapter leans on He Yun had originally wanted to try making braised fish under Jiang Li's....