Yeah, you'll learn more about Ghostfreak in
Ghostfreaked Out. It's one of my favourite episodes. Ghostfreak's scream when he disintegrates at the end of the episode is actually kinda ear-piercing.
Despite that, Ghostfreak's one of my favourite aliens. His transformation's one of the creepiest. Though Kevin never liked him.
Apparently the Codon Stream got a different sample of Ectonurite DNA by Ultimate Alien. Speaking of Ultimate Alien, before his death, I heard Dwayne McDuffie said that all aliens in the intro will appear. But they didn't. Too bad, cause I always loved Ditto. He was so funny in
Divided We Stand!
If you get confused while watching any of the episodes, don't hesitate to ask me. You shouldn't need me, the shows are pretty straight forward.
And btw,
Destroy All Aliens is the finale of Ben 10. Though you could swap it round with
Race Against Time.
Alien Swarm probably takes place in between
War of the Worlds and
Vengeance of Vilgax. I'm not sure.