Double edit:here is my OFFICIAL MLP Version of Voltron:Legendary Defender:
 
Twilight Sparkle as Takashi ‘Shiro’ Shirogane  
Rainbow Dash as Keith Akira Kogane  
Sky Stinger as Lance McClain  
Moondancer as Katie ‘Pidge’ Holt/Gunderson  
Pinkie Pie as Hunk Garret  
Princess Luna as Allura  
Rarity as Coran

@Background Pony #D808  
Edit:I actually now think that Sky Stinger makes a better Lance McClain than Lightning Dust.

Eeeehhh, I rather see this the other way around:with Applejack as Lance, and Rainbow Dash as Keith…mainly just because I like the idea of Keith Kogane!Rainbow Dash a HELL of a lot btter than I do Applejack as Keith…besides, Keith and Rainbow are both hotheads, and AJ’s not, so…yeah, there’s that characterisation logic. This is how I would personally see things cast as, as of Season Seven of MLP:
 
Shining Armor (or, alternatively, Twilight Sparkle) as Takashi ‘Shiro’ Shirogane  
Rainbow Dash as Keith Akira Kogane  
Lightning Dust as Lance McClain (she’s the only one that’s a close enough rival to Rainbow, so this makes the most sense to me)  
Twilight Sparkle (or, alternatively, Moondancer) as Katie ‘Pidge’ Holt/Gunderson  
Pinkie Pie as Hunk Garret  
Princess Luna as Allura  
And Rarity as Coran (because why the hell not?).
 
So, yeah…there’s MY take on this whole ponies-as-Voltron-characters thing. 😕 There ya’ll go, I guess.