From Chapter 10 of Rainboom and Crystal Ninjas.
The Rainbooms and Shadowbolts bring the rest of team Wondercolt (Flash Sentry, Sandalwood, Micro Chip, Lyra & Bonbon, Derpy) and the CMC'S to the Turtle's lair. Later, while training, the CMC'S walk in and show off their new ninja weapons, that Mikey gave them, much to the Turtles and Rainbooms shock. Rarity tells Mikey that he should have asked them before giving the girls weapons. Rainbow Dash, on the other hand, dosen't have a problem with it much to Rarity and Applejack's chagrin.
"What? We all have weapons. And we're good with them."
- Rainbow Dash
But in Chapter 11 when the Wondercolts and CMC'S are captured by Scumbug and Antrax and brought to Spiderbytes to be dinner, they help the Turtles; Mutanimals; Rainbooms and Shadowbolts defeat them. Afterwards Rarity and Applejack admit that the CMC'S really defended themselves. But when Sweetie Belle asks if they can train to be ninjas too, Applejack tells them not to push it.
Equestria Ninja Girls: Rainboom and Crystal Ninjas by DarkMagicianmon a.k.a Wildcard25.
Applejack, Rainbow Dash, Rarity, Apple Bloom, Sweetie Belle, and Scootaloo's Weapons by BozzerKazooers