ATTACK RIDE

[kamenriderdecade]

Despite relying on form changing a lot, Tsukasa does have his own form, and his own abilities, though quite a few of them are borrowed from other riders. He can simply use them through his own personal form.

 

As of the second movie, his default state is now referred to as VIOLENT EMOTION.
His default state is a jack of all trades, but in the 'master of all' sense.
He's an able fighter barehanded and has gone toe to toe with some of the best fighters in the kamen rider universe and won.
The ridebooker, which is a carrier case for the cards he uses to fight, functions as both a gun and a sword.
He's incredibly skilled with both of these as well.
His true strength shines through the use of his ATTACK RIDE cards.
They grant him extra abilities, and although originally he could only use cards specific to him, his violent emotion form can use any of the following cards without restriction

ATTACK RIDE
SLASH
Powers up the attacks of Decade's blade, charging it with energy.
BLAST
Improves the firing rate of his gun, allowing it to rapid fire.
ILLUSION
Creates 2-6 physical copies of Decade, that can fight independently of him.
INVISIBLE
Turns decade...invisible. SHOCKHORROR
CLOCK UP
Allows Decade to travel at speeds of up to mach 60.
AUTO VAJIN
Turns Decade's bike into the Auto Vajin mech. It stands at roughly six and a half feet in height
and is equipped with a gatling gun, shield and flight capabilities.
METAL
Transmutes Decades body into a bio-organic metal.
MACH
Moves decade into an accelerated time plane, allowing him to react and move faster than the outside world.
GIGANT
Summons Kamen rider G4's gigant which is a shoulder mounted rocket launcher.
SIDE BASSHAR
Transforms Decades bike into the Side Basshar, a walker mech equipped with numerous weapons.
HYPER CLOCK UP
Allows Decade to move at beyond light speeds and time travel.
TERIBIKUN
Summons the nine heisei era riders in their strongest forms.
Alongside his rider kick, they preform their strongest finisher on the target.
 

This is Decade's COMPLETE FORM gained through the use of the K-touch device.
It acts in a similar fashion to his default form, with one exception. He can now summon the other riders.
He presses a symbol on the K-touch that represents that rider, which summons that rider to his side.
The summoned rider will shadow every single one of decades movements.
If he initiates a final attack ride, both the summoned rider and Decade will use that riders strongest attack in unison against the foe.
With the teribikun card, he can summon all nine riders and preform all of their attacks at once. He will preform his rider kick with them.
Aside from that, it doesn't do much aside boost his strength.