The Young Alicorns against the Nightmare family and Bill Cipher

Here is how Princess Yuna and her cousins begin their fight against the Nightmare family in Genesis World.

Later, The Nightmare Family are about to take over Genesis World.

King Sombra: At last. Genesis World is ours now!

Princess Yuna: Not today, Sombra!

Nightmare Moon: Princess Yuna!

Nightmare Rarity:

Nightmare Trix: (blasts Yuna) Take that, Princess!

Nyx: Hey! No Pony does this to my cousin!

Princess Jubilee: It's over!

Nightmare Moon: All of you stand down while you still can!

Princess Yuna: NEVER!

Nightmare Moon: Fine!

As Nightmare Moon prepares to fire, A loud roar came.

Heather: ROOOOOOOOOOOOOOOOOOOOOOAAAAAAAAAAAAAAAAAAAAAARRRRRRR!!!!!!!!!!!

Cerberus the Nightmare Train: The T-Rex!

Princess Yuna: Good girl, Heather. (pets her) Good girl.

Yuna opens the portal to Tartarus.

Princess Twila: Say hello to Aku.

The Nightmare Family: NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!

Princess Yuna: That takes care of them.

Princess Skyla: What about the Piranhaconda?

Princess Twila: We gotta get rid of it once an for all.

Princess Yuna: And we will. Come on!

Yuna and her cousins begin searching for the Piranhaconda.