This is how Rarity and Bumblebee vs. Optimus and Twilight goes in My Little Pony Transformers: The Last Knight.
[We see Rarity and Bumblebee getting ready to battle Optimus and Twilight]
Rarity: Let's do this.
[they charge at Optimus and Twilight and engage in combat against them]
[Bumblebee and Optimus face off]
Optimus Prime: I am Nemesis Prime! You are nothing!
[Rarity and Twilight face off]
Twilight Sparkle: I am Nightmare Sparkle! You are nothing!
[Rarity gets out her magic hammer]
[Bumblebee then stops Optimus' blade]
Bumblebee: I-I am Bumblebee...your oldest friend! Optimus...I would lay down my life for you.
[Optimus' optics turn blue again]
Optimus Prime: Bumblebee. I have not heard your voice since Cybertron fell.
[We see Rarity trying to talk to Twilight]
Rarity: Twilight, I will always be your friend.
[Twilight tries to bring her horn down on Rarity]
[Twilight sees Rarity has stopped it]
Rarity: I would lay down my life for you, even to avenge you.
[Twilight's eyes transition from red to purple again]
Twilight Sparkle: Rarity. I don't know what came over me.
[Twilight backs up]
[Bumblebee pulls his parts back to him, putting himself back together]
[Megatron suddenly attacks with Nitro Zeus]
[He knocks down Optimus and Twilight]
Megatron: Quintessa, the most ruthless of our planet, knew you couldn't do it. She knows I'm strong and you're weak.
[He steals the staff from them]
Megatron: You turned your back on Cybertron. Now you will watch Equestria die.
[They fly off as a Cybertronian knight comes out and punches Optimus and Twilight]