I’m more of a casual fan than a brony, but for me perhaps the most obvious thing that stands out about My Little Pony: Friendship is Magic is how so many of the cast members have previously appeared in Ranma 1⁄2. Off the top of my head, the Ranma cast who have gone on to voice Pony characters include…
 
Richard Ian Cox (Male Ranma) as Snails, Dumbbell and a few other minor characters  
Cathy Weseluck (Shampoo) as Spike and Mayor Mare  
Ian James Corlett (Jusenkyo Guide) as Silver Shill  
Nicole Oliver (Yotaro’s mother, Miyo and Rinko) as Princess Celestia and Ms Cheerilee  
Tabitha St. Germain (Yuki Onna) as Rarity and Derpy Hooves  
Matt Hill (Pantyhose Taro) as Soarin  
Michael Donovan (Ryoga Hibiki) as Globe Trotter (that lost tourist outside Fluttershy’s house - how ironic!)  
Sylvia Zaradic (Kodachi Kuno in seasons 5 and 6) as Cherry Jubilee  
Saffron Henderrson (Tsubasa Kurenai) as the Daring Do Collector in the Trade Ya! episode  
Ellen Kennedy (Madame St. Paul) as The Mane-iac  
Kikiko Inoue (Kasumi Tendo in the Japanese dub) as Princess Celestia in the Japanese dub
 
Even other Ranma cast members such as Brigitta Dau, Venus Terzo and Willow Johnson have apparently done voice over work in older versions of My Little Pony. But perhaps the newest and biggest one to that stands out is Kelly Sheridan (Ukyo Kunoji) as Starlight Glimmer. In season 5, it took me awhile to catch on and recognize her voice. If you listen closely you notice the similarities, it almost sounds like Ukyo putting on an upperclass voice. But in today’s two episode, it’s much more obvious and you don’t need to listen closely to recognize it. Her Ukyo voice shine through very noticeably this time around. Once you hear it, you can’t un-hear it! I thought it was hilarious seeing Ukyo’s voice come out of Starlight’s mouth. It’s as though Ukyo has fallen into the Spring of Drowned Unicorn.