This is how The Seekers learn of the gems goes in Transformers Generation 1: Battle of the Bands.
[The movie begins in the Decepticon headquarters]
Thundercracker: [growls] Those Autobots and ponies are really starting to get on my nerves!
Skywarp: You're telling me!
Starscream: Will you both get a grip?! By Primus! And I thought the Dazzlings were tough to beat!
Skywarp: The Dazzlings?
Thundercracker: Who are they?
Starscream: Three sirens who were banished from Equestria long ago. They possessed gems that could not only control the people they were singing to but also absorb the negativity and distrust of others. They needed the negativity and hate to maintain their enchanting voices.
Thundercracker: Wait. Aren't those three the girls who tried to take over Cybertron but were defeated by Alpha Trion?
Skywarp: However, getting their power from the human universe was barely worth the effort.
Starscream: The energy there wasn't the same as in Equestria. They could only gain so much power there.
Skywarp: Ugh! I wish we'd never been planted here in the depths of the ocean!
Starscream: [sarcastically] Oh, really? I love it here.
Thundercracker: For real, now? Because I think it's the worst.
Skywarp: I think you're the worst, Thundercracker.
Thundercracker: Oh, yeah? Well, I think you're...
Starscream: Ergh! I'll tell you one thing: being stuck down here with you two isn't making this planet any more [through clenched teeth] bearable.
[Starscream then gets an idea]
Starscream: Are you thinking what I'm thinking?
Thundercracker and Skywarp: I 'unno.
Starscream: I'm talking about the use of Equestrian Magic!
Skywarp: But this planet doesn't have Equestrian Magic.
Starscream: It will soon. And soon we'll be able to use it to make everyone on this pathetic little planet bow to our will.
[They head to Equestria where they find the gems used by the Sirens in a cave]
[Hasbro Gaming presents]
[A Hasbro Studios production]
[Transformers Generation 1: Battle of the Bands]