Nuke87654

I'd say between 20-24 (I know I'm cheating). The reason for this is because of this scene from Pinkie Pride: In this image, Rainbow Dash's cake is shown 21 candles. Considering how fanon has Rainbow Dash among if not the youngest of the mane 6, this likely indicates that the rest of the mane 6 is likely in their early 20's and at oldest mid 20's.

According to the Journal of the Two Sisters, Celestia was implied to be the stronger of the two sisters. Also, Nightmare Moon was shown to have provided a significant power boost to anyone who it posses, it what allowed Rarity, a normal unicorn, to be able to beat a depowered Luna in a fight. Also, Celestia was shown not to have fought her sister but rather she tried to avoid her fire, heck she even said this: Princess Celestia: Luna, I will not fight you! You must lower the moon! It is your duty! This shows that Celestia had no intention of fighting back. She used the EOH more likely as a quick means to defeat Nightmare Moon and have a chance to try and rescue her sister from Nightmare Moon's influence. As I mentioned from the comics, Reflections arc showed Celestia has a power form that she didn't used against Nightmare Moon on the show.

The two characters I've presented to you are the comic content creators Katie Cook and Andy Price's OC ponies respectively. These pony ocs were first shown in the show in the episode Princess Spike. Is that good enough to show the comics are canon?

That was said mainly to keep those who hated how the comics are portraying the series complacent. You can ask Coffee Pony, a long time Transformers fan, that whatever official material Hasbro put forth for their brands universes such as comics and show, it's considered canon unless it were to contradict the main one such as the shows, than the show is considered above it. I consider the comics canon regardless and I don't see the point for expressing that you haven't read the comics to be a valid point. I haven't read the new ones since last year but that doesn't' stop me from considering any of the future comics canon. Besides, it's not just the comics that said Celestia's more powerful, the Journal of the two sisters, written by Amy Keating Rogers, also implied that Celestia is more powerful. No, Andy himself was being very specific when he said that so long as the show doesn't contradict the comics, whatever material the comics put forth is canon. I would trust his word on the matter considering who he works for. Star Wars expanded universe canon, before Disney nuked it to high hell to replace it with a new one, was considered canon and a part of the Star Wars universe so long as it doesn't contradict the movies or material officially supported by George Lucas such as the Clone Wars cartoon show canon itself. It merely expanded upon the many characters and timelines in the Star Wars verse that the movies and other materials themselves were too insufficient in number to be able to do.

https://mobile.twitter.com/andypriceart/status/461550768492150784 That evidence doesn't explain how she got the ability to be nightmare moon but her first time rebelling against her sister as Nightmare Moon. http://www.equestriadaily.com/2015/02/clarification-on-mlp-comics-vs-show.html More clarification about the issue on Eqd. Essentially, the comics are 'B' canon to the show's 'A' canon. Similar to the relationship the expanded universe and the movies and other official media of Star Wars share, so long as it doesn't contradict anything the show considers as canon, then the comics canon can coexist in MLP gen 4.

The comics established the background for how Luna got Nightmare Moon form an outside source and it is not something she can achieve on her own. Until the show says something different, it is canon. Because she was giving her sister a chance to stop her madness only for her sister to attack her in turn. Then she decided to banish her to the moon before anything else can happen. As for the first two episodes, it was pretty much implied that she likely lost on purpose so she can pull a gambit where the mane 6 can become the new elements of harmony bearers just so she can free her sister from Nightmare Moon. Celestia: Twilight Sparkle, my faithful student. I knew you could do it. Twilight Sparkle: But... you told me it was all an old pony tale. Princess Celestia: I told you that you needed to make some friends, nothing more. I saw the signs of Nightmare Moon's return and I knew it was you who had the magic inside to defeat her, but you could not unleash it until you let true friendship into your heart. Now if only another will as well. Princess Luna!