CHECK THIS OUT!(NOT MINE, SCREENSHOT+EXTRA)

And THIS is the motto these guys used:

Ash: Prepare for trouble!
Brock: And make it Double, Double!
James (angrily): Uhh, quit imitating us!
Misty: To protect the world from devastation!
Duplica: To ignite all people within our nation!
Jessie (angrily): Err! This is insulting!
Ash: To denounce the evils of truth and love!
Misty: To extend our reach of the stars above!
Ash: Ash!
Misty: Misty!
Brock: And Brock!
Duplica: Duplica, that's right!
Brock: Team Rocket blast off at the speed of light!
Duplica: Surrender now, or prepare to fight all of us!
Pikachu: Pika, Pika!

Isn't this hilarious? That's just one of the times they imitated Team Rocket. Here are yhe other mottos used, in other episodes:

Ash: Prepare for trouble!
Misty: And you can make that triple!
Brock: To protect the world from devastation!
Ash and Misty: To unite all peoples within our nation!
Jessie (stunned): This was just...
James (stunned): Too good...
Meowth (stunned): To last.
Ash: You got that right.
Pikachu: Pika!
Misty: We're defending the beauty of truth and love!
Brock: Let's do it!
Meowth (interrupting them): We gotta stop that!

Ash: Team Rocket, prepare for trouble! On second thought, make that double!
Jessie (surprised): To protect the world from devastation?
James (surprised): To unite all peoples within our nation?
Ash: Maybe you think I'm a little too brash. But the master is here and my name is Ash!
Pikachu: Pikachu!
Ash: My Pokémon team is faster than light! Surrender now or you're in for a fight!
Meowth: Meowth! That's right!

Dawn (really angry): Get ready for trouble!
Pikachu (really angry): Pika!
Brock (really angry): Make it double!
James (shocked): Hey, no fair!

Ash: Listen, is that bad guy talk I hear?
Dawn: It speaks to me loud and clear!
Ash: On the wind!
Dawn: Past the stars!
Brock: In your ear!
Jessie (interrupting them): It's that kind of imitation they invented lawsuits for!
Dawn: Chill out! We couldn't care less about you.
Ash: We're looking for Spiritomb!