This is how Starscream turns the Autobots into Sparklings goes in Sparkling Problems.
[The Autobots and ponies head to Starscream's location, the Harbinger]
Optimus Prime: Starscream and Hardshell should be inside.
Arcee: [to the ponies] Stay here.
Bumblebee: It's not safe for you Equines.
Bulkhead: We need to keep you safe.
Ratchet: Let's go.
Wheeljack: We'll take them completely by surprise.
Ultra Magnus: Be cautious, you two.
Knock Out: Starscream sure does pack a punch with his claws.
[They enter the ship and look around]
Arcee: Guess we must've missed them.
[Starscream lands in front of them]
Starscream: Hello, Autobots.
[The Autobots ready their weapons]
Starscream: No need to fight me with guns.
[Starscream brings out his own gun and powers it up]
Starscream: Say hello to the Sparkling Ray! [fires it]
[The Autobots scream in pain. Hardshell watches in joy while Soundwave surprisingly turns his head away in shame]
[The Autobots shrink and turn into Sparklings]
Sparkling Optimus Prime: Uh, what happened?
Sparkling Wheeljack: Where am I?
Sparkling Bumblebee: [to Sparkling Arcee] Hi, what's your name?