This isn't a complete episode guide. I've tried to list only the episodes that focused on Aisha… and there aren't very many of those! I've also included eps like "Wild West Rangers" that had some special importance for the character.

Season Two

The Ninja Encounter Pts. 1-3
Aisha makes her debut as a member of a ninja team from Stone Canyon. After being captured by Lord Zedd, she, Adam, and Rocky learn the Rangers' identities.

The Power Transfer Pts. 1-2
Aisha becomes the Yellow Ranger when Trini is chosen to go to the Peace Conference.

Where There's Smoke, There's Fire
Aisha becomes a fire safety captain and gets a little obsessive about it. Includes a memorable conversation… "Whoa, you gel before you curl!?"

Forever Friends
Shawna, Aisha's best friend from Stone Canyon, becomes jealous of Kimberly.

Rangers Back In Time Pts. 1-2
Lord Zedd uses the Rock of Time to turn the Rangers into children. This is the first episode to feature Young Aisha, played by Sicily Sewell.

Wild West Rangers Pts. 1-2
This episode really focused on Kimberly. However, it did feature Miss Alicia, Aisha's ancestor from circa 1880.

Season Three

Stop The Hate Master Pts. 1-2
PR's most Aisha-centric episode. Aisha is depressed over not being accepted to the Angel Girls' Club. Meanwhile, the Hate Master attacks and turns the Rangers against each other. Only Aisha seems to be immune, and it's up to her to save the team.

The Sound of Dischordia
Aisha and Kat enter a contest to rewrite Angel Grove's school song. Then, Lord Zedd sends Dischordia to attack the Rangers.

Hogday Afternoon, Pts. 1-2
Young Aisha travels to Africa to find the Zeo II subcrystal, and ends up sending Tanya back in her place. This episode is Aisha's final appearance.

Season Four

The Lore of Auric
Aisha is mentioned (but not seen) in this episode. She mails Tanya a package with some of her parents' effects, including Auric's golden key and a map to Mysterio Island.