Rachel and Kirsty saving the Rainbow Fairies, particularly in Heather's book, where Jack Frost is captured in a snow globe.
Holly the Christmas Fairy's book has the girls captured by Jack Frost. When all seems lost they trick him into wearing King Oberon's crown, which teleports him away.
In Storm the Lightning Fairy's book, an extra-mean goblin with red eyes shoots fairy lightning at the girls with the power of the Lightning Feather. While it isn't as dangerous as real lightning, it's still very threatening, to the point that no one in the entire book is hit by it directly. It gets close enough to burn Rachel's coat and Kirsty can feel its heat on her face, and it leaves scorch marks on the floor.
Doodle saving Rachel and Kirsty from Jack Frost at the end of the Weather Fairies series.
Sophie the Sapphire Fairy's book has the girls attacked by goblins at a public fountain, and Sophie's sapphire is in the water with the goblins. Kirsty tried and failed to get the gem, so the girls wade into battle together with an umbrella to block shots from the goblins' squirt gun.
Gabriella the Snow Kingdom Fairy's book is full of awesome moments.
To rescue her magic snowflake, Rachel and Kirsty ski down a mountain to catch up to the goblins.
Later, to get back her festive spirit (kept in a jar) they dress up as delivery girls with an amazing cake to get into the Ice Castle. When this doesn't work, they let themselves be captured so they can trick Jack Frost into revealing where it is.
Book 7 of the Sports Fairy series has Jack Frost trying to cause trouble in the finale—until the Fairy Queen zaps his wand out of his hands and keeps it til the games are over.
The Petal Fairy series is one for the goblins, as they have Jack Frost's ice wand to cause major mischief.
In Olivia the Orchid Fairy's book, Rachel and Kirsty chase the goblins to a frozen waterfall and hold them hostage as it begins to melt, saying that unless they give up the magic petal they'll stay there as a waterfall crashes onto them. They give in pretty fast once it starts to melt.
In Destiny the Pop/Rock Star Fairy's book, human ushers get one when they escort Jack Frost out of a theater for being too loud; this allows Rachel and Kirsty to get Destiny's magic microphone back while he's distracted.
In Elisa the Royal Adventure Fairy's book, Rachel is frozen solid by Jack Frost. Elisa tries to tell Kirsty that going in there is dangerous, but she refuses to back down because her friend is there and in trouble.
Jack Frost got one in Frankie the Makeup Fairy's book (part of the Pop Star/Superstar Fairies set) when he trapped Rachel and the magical clef in a makeup box, then teleported the box, the clef, and himself back to his castle in Fairyland.
In the Superstar Fairies series, Jack Frost manages to fool the girls with his Jax Tempo disguise until the 6th book of 7.
The first Fashion Fairy book has Jack Frost zapping Queen Titania and replacing her crown with a wool hat.
Jack Frost gets an unintentional one in Keira the Movie Star Fairy's book. His shouting orders through the magic megaphone made it impossible to get close to him until Keira summoned earplugs.
The entirety of the Green/Earth Fairies series for teaching about the environment and showing that it's up to humans; while the fairies can help in-story, it's up to humans to truly fix things. Rachel and Kirsty are discouraged at first because it's such a big job for two girls, but by telling others, who then tell others, they feel encouraged that the planet can be saved.
They help out a lot of animals and places throughout the series as well, saving a deer from drinking polluted water, helping a seagull stuck in trash, and helping a coral reef that had been damaged by goblins and humans.
The music for the "Create a Fairy" game on the website.
The movie has Rachel and Kirsty standing up to Lydia, believing in fairies and each other. This causes Lydia's posse to befriend them, and eventually results in Lydia making a Heel-Face Turn.