Kabuto's strongest enemy is...

[Ryoutarou]

In episode 39, we're going to see the final enemy of the series. Apparently this Tendou is trying to stop TV Tendou from taking Hiyori back to the past/present. Either way, they're going to the future.
http://img82.imageshack.us/img82/2135/1161473261692vp2.jpg
http://img95.imageshack.us/img95/7254/1161473273599mf2.jpg

[Kamen Rider]

Here's the full pic of Dark Kabuto.

http://img180.imageshack.us/img180/4016/1161519021085pc0.jpg
(From 101fwy.net)

[Ryoutarou]

http://img228.imageshack.us/img228/4953/2002429653030351198rsdb9.jpg
http://img228.imageshack.us/img228/8113/2002445432783253258rsvn5.jpg
http://img228.imageshack.us/img228/3285/2002439640370712622rske7.jpg
http://img228.imageshack.us/img228/5457/2002461882494053369rsam7.jpg


His attack is "Dark Rider Kick".

Translation:
"Dark Kabuto- the transformed state of a man who uses the Dark Kabuto Zecter, and looks just like Tendou Souji. He is the strongest warrior, born to destroy Kabuto."

The last pic says that "Mimic Tendou Souji" is a "Worm copying Tendou's form and heart" (his feelings for Hiyori.) So I am guessing he probably will think he's the real deal or something.

There is also an item known as the Dark Kabuto Hyper Zecter"

[Rider_Leangle]

Man this is old news, But thats wrong, Tendou's strongest enemy is them
http://www.youtube.com/watch?v=bEvsUtZEMSU