By “base”, I mean Saber can’t transform without Dragon, Blades can’t transform without Lion and Espada can’t transform without Alangina.

Exaggerating for sure, but I would have totally believed it if you said he was 16/17 like Masaki Suda and Shun Nishime were when they started W and Ghost.

As for Kento & Touma I was assuming that if it does do something to ageing (could still just be that Slash looks young for his age and Buster looked older than he was in the past) then that would only happen when they became the wielder of a Seiken, so wouldn't have been the case 15 years ago. Luna I couldn't even speculate about, I'd love her to be a rider in Q2 but we really don't know enough yet!

And do you have a quote for that? That's all it'd take, preferably in the form of a screenshot from the show.

It’s going off the hypothetical form generator and the toys. The former automatically inserts one of those three books depending on who you chose and the latter doesn’t produce any unique sounds with the other books without that one that came with the emblem.

So what happens if you use all their 'base' books at once. I wanna see that. Surely that's something they've got planned for the movie or something

According to the hypothetical form generator, it's just like any other three-book Wonder Rider. But it would be awesome if in the story combining their three base books did something important, like maybe create a shared power-up for all three of them based on the Three Musketeers!

Okay, it's canon for the time being.

The latter isn’t fully true. The 9 Wonder Combo books all have unique jingles when used by themselves, something that would be an odd thing to implement if they didn’t intend for that to be theoretically possible (though it is true that, say, Pegasus and Peter don’t get a special jingle like Pegasus/Lion and Lion/Peter do).

Oh for sure, your theory that Seiken Swords freeze or slow down aging is actually quite plausible so far.

I was only disputing Kurona's speculation that the reason is biological rather than magical, to which I contested that Kento and Daishinji don't age consistently with each other.

It's also plausible as you say that Daishinji simply looks really good for his age. Zero One had a more extreme example with a 45 year-old character played by a 22 year-old so there's a chance that we're overthinking it like people, myself included, did with Gai.

That's what I believe as well. It would be counterproductive for Bandai to deliberately program the Seiken SworDriver to make the Brave Dragon "base" book non-variable when used in Rekka mode, effectively turning Saber in to a lesser Build instead of the better OOO he's designed to be, as conveniently shown in your collection. The lack of Pegasus Peter jingle for Blades on the other hand can be justified as a feature they simply decided not to include.

How would you all picture the South Pole’s swordsmen?

What if their drivers were shields?