I was thinking about that whole character customization shebang, and how Palutena and Mii Fighters are so heavily (if not inextricably) linked to its existence. Basically, those two (four?) exist to show off added diversity in customizable movesets (in that, while most characters only have variations of their stock special moves - you can't de-equip Mario's FLUDD, for instance - those two have three completely unique special moves available for every single direction). Obviously they'll have some interesting capabilities beyond that, but, in a somewhat cynical take on things, that
is their primary gimmick here.
But the customization options don't stop at swapping out special moves; I distinctly recall Sakurai was talking about the ability to buff stats, at the expense of nerfing others simultaneously. Looking over
the character customization page (seriously, these read kinda like lengthier Dojo articles, it's great), it appears you get three slots to put various items that buff either attack, defense and speed, while nerfing another of those three. You can use this to your advantage, choosing to only use items that buff a given stat, for instance.
Now, going back to how people were speculating Shulk might work - the whole gimmick of
Xenoblade is using each character's Arts to inflict various statuses on enemies, like Shulk using Stream Edge to inflict Break, then having Reyn use Wild Down to Topple it (which can only be done on enemies suffering Break or Daze, or already Toppled), then have Sharla quickly hit them with Head Shaker to inflict Daze... things like that. In addition, you could also give yourself various buffs with the various Arts - the Monado can boost your attack (against Mechon, anyway), speed or defense (with Monado Enchant, Monado Speed and Monado Shield, respectively); for a less Monado-centric example, each of Melia's Summon <element> Arts grants her a small stat boost, like a weak HP regeneration for Summon Aqua, or a boost in Agility for Summon Wind.
So what I'm thinking is, maybe Shulk is supposed to be an example of this stat-boosting, outside of the modes where stat-boosting via items is allowed? Basically, he'll be using his Monado Arts to boost one of the three stats for himself (or potentially lower it for others - doubt
that one will happen, but you never know), to sort of exemplify the perks of what boosting that particular stat could do for the other characters. Obviously, the boosts would be large enough to be noticeable. I'm not sure if each buff would have an accompanying nerf, given it's inconsistent between items which stat nerf gets paired with which stat buff, or the degrees to which the two are linked, but it'd make sense, too (might as well exemplify the downsides if you're gonna exemplify the upsides). Assuming this is all true (we don't know for 100% Shulk's even in the game, although it's looking likely - and even if he is in, we don't know he'll be centered around stat buffs/nerfs), that's actually a pretty clever way of letting players experiment with it without necessarily having items on hand.
