This is how Autobots stay on Equestria goes in Darkness Rising Part 5.
Twilight Sparkle: We did it!
Rainbow Dash: Yeah!
Pinkie Pie: Alright!
Fluttershy: [quietly] Whoo-hoo!
Optimus Prime: We would be honored to stay.
Twilight Sparke: That's great Optimus.
[We see Applejack and Bulkhead at Sweet Apple Acres picking apples]
[We see Fluttershy and Ratchet at her cottage]
[We see Pinkie Pie and Smokescreen at Sugar Cube Corner]
[We see Rarity and Bumblebee at her boutique arranging dresses]
[We see Rainbow Dash and Arcee at the Wonderbolts Academy training]
[We see Twilight Sparkle and Optimus Prime at her castle learning]
Optimus Prime: (narrating) Without a means of leaving this world, we Autobots take strength in the bonds we have forged with our pony friends - true warriors, who represent the Elements of Harmony, as do we. My name is Optimus Prime, and I send this message. Though we did not choose to be of Equestria, it would seem that we are here to stay. If you approach this planet with hostile intent, know this: We will defend ourselves. We will defend the Equines. We will defend... our home.