Bleach V: Well that was a waste of time (Fullbring? What's that?)

[Calemyr]

If they weren't in gigai during the fight, where were their shinigami uniforms? As we can plainly see from both TBTP and the end of the Fullbring arc in Soul Society, their shinigami bodies still have uniforms. If they were not in gigai, they would have these uniforms during the battle as well.

Would they? While important to the Soul Reapers, their uniforms are not intrinsic to their being. High ranking Soul Reapers often carry accessories or customizations that are not standard, such as Renji's glasses/headband or Korraku's hat or Yamamoto's oversized haori or Kenpachi's tattered one. Nor is the appearance of the Soul Reaper exactly bound to the appearance of their physical body, as seen by the captains' tendency to wear time-appropriate clothing on their gigai. (Also, jokes have been made, at least in the anime, about swapping gigai to freak the newly spiritually blind Ichigo out.)

The Vizard, however, do not have any ties to the squads anymore, so they have no uniform to wear. As such, they dress their gigai in the same style they dress themselves. When they are given a uniform to wear again, they do so with pride.

Aizen explained this at the end of the rescue arc; Rukia's gigai was designed to drain all her spiritual power away (turning her into a Plus) so as to hide her soul, and within it Urahara's Hougyoku. Hers was a unique case and does not apply to the Visored because they had no Hougyokus of their own to hide.

The role of the Hougyoku makes that instance questionable, as that thing also triggered powers Orihime and Chad where none were previously evident. Either way, whether gigai can manage some kido is less the question than whether it can manage enough to be martially effective. Remember that Don Kanoji is capable of minor kido without any actual training, so a purely physical body isn't completely unable to do so.

Also, Urahara's use of disposable gigai as distractions in battle suggest that they aren't entirely incapable, though how much of their stunts is Urahara trickery and how much can be applied to more permanent, commercial products is unknown, which renders it largely ineffective as a point in this argument for either side.