Kaguya hasn't shown any speed that's special, neither have Naruto or Sasuke for that matter. Even if he reacts to them, it won't say much speed wise. At least not against Guy.
If by speed that's special, you mean anything visually impressive that looks like it can be fan-calculated (like distance traveled/time interval) or physics-breaking then no. Although that's a relatively narrow way to quantify speed by flashiness, when there's an obvious power hierarchy that does tell us that Kaguya > full-power Juudara > 8-gates Gai in reactions. And Current Naruto just went about speedblitzing the strongest character in the series, which says A LOT about him speed-wise, as he'd be the fastest character to date. Sasuke himself is at a speed where the same Juudara that Gai nearly kicked admitted to be particularly fast. If Kakashi does indeed react to anyone of them, he certainly would be able to see and counter Gai's speed. Maybe not with his PS precisely, but a mix of dimensional intangibility and instant Kamui would do.
Except none of those three are as fast a Gai.
That's ridiculous. Are you insinuating that Gai is the fastest character in the series, when the second to last chapter showed a character who's significantly faster than him in feat?
Speedblitzing Kaguya >>> Speedblitzing a one-eyed Juudara.
I don't think Juubidara at full power showed ANY sort of speed to match Gai's, nor has Kaguya or Naruto or Sasuke. If they had, they'd be running circles around each other similar to what Guy was doing against Juubidara. Intsead they've had to plan out their attacks carefully, use a DUMB F**KING sexy Jutsu, and use the power of friendship to suddenly punch her in the face. Show me a feat where any of them moved so fast that they were noted to be bending the space around them with speed alone. Look, just because someone is the strongest in the verse, that doesn't mean they're the fastest. As it stands, I believe Guy is the fastest one in Naruto, bar none. Hell, he'd probably do better in the fight against Kaguya than either Naruto or Sasuke, who he should be on par with in 8 gates.
@takashichea: thanks sorry about that, sometimes I just get too lazy to save and upload a pic -.-'
@taichokage: Lol Naruto just needs to hurry up and end, let's put it that way. It's getting on my nerves and I hate it more than ever. Guy was really the only saving grace for me in the past months. They should have just ended it with Madara instead, who was a good villain til he was plot deviced to his death :P
@takashichea: Trust me, One Piece will never take that turn. Oda takes his time with story, and that's why he's still going strong and barely over the half way point of the series. Despite the slow pace that he can instill at times, it just goes to show that he's focused on the plot and not some big ass power up out of nowhere. It's already been two or three arcs since the time skip, and honestly Luffy and Zoro are just barely showing what they can do. Bleach was a lost cause from the get go though, full of repetitive story and stuff like that :P