Introduction:
It's not every day that a character swings from bottom tier to top tier in the span of two years, but that was the case for Dragunov going from his first game (Tekken 5: Dark Resurrection) to Tekken 6.0 (often referred to as "vanilla"). Below I'll cover notable differences from version to version, specifically changes to general properties, safety, and speed. Minor differences in frame data (unless unsafe to safe and vice versa) as well as minor differences in damage (unless notable for one reason or another) will not be mentioned.
Tekken DR to Tekken 6.0
1,1,3 is now safe on block
CH (1,2),1 now launches, requires a quick iWS+4 follow up for full juggle
(2,1),3 can now be delayed
(2,1),4 can now be delayed
3 has been completely reworked, instead of being NH KND/W! it's now part of a new string, now hits mid
4 has lost its "magic 4" properties, interesting enough though that CH (f+4),4 still retains magic 4 properties
4,3 has been completely reworked, instead of KND/W!, it now spikes the opponent for a guaranteed d+3+4 on CH
f+1+2 now launches on hit instead of just basic KND/W!, as such it's now -12 on block
f,f+2 has been reworked somewhat, now leaves the opponent FDFA instead of FUFT
f,f+2~1+2 throw speed increased, damage increased to match DR's Ki charged f,f+2~1+2, 6.0's Ki charged f,f+2~1+2 deals no additional damage
CH f,f+2 no longer launches, instead it KND the opponent into a techable state, only fast follow ups are guaranteed
f+3 has been reworked, no longer gives huge +frames on CH and can no longer low crush
f,f+3 has been completely reworked
f,f+4 no longer crushes highs or lows at any time during the animation
(b+3),1 has been removed while b+3 remains the same
b+4,3 now KND/W! on NH, still hits m,h non-jailing, speed increased drastically
b+4,2,1 speed increased drastically, animation has been improved
b+4,2,1+2 tackle speed increased
d+2 on CH is now +4 and damage sparks, while enraged d+2 sparks on NH as well as CH
d+3,4 is now NCc, d+3 now consistently hits grounded opponents but is also now launch punishable
d+4,1 recovery speed has been tinkered with, e.g. d+4,1, d+4,1,3 no longer works for any of Dragunov's launchers
d+4,1,3 is no longer launch punishable on block, although it's still l,h,h with all hits being non-jailing
d+4,4 has been completely reworked
(d+4,4),3 has been removed completely
u/f+3+4 speed has been drastically reduced, damage increased to counteract Tekken 6 throw damage "nerfs"
d/b+2,1,2 is no longer NCc, instead d/b+2,1 is NC and (d/b+2),1,2 is NCc. Entire string delayable and now only -14 on block
qcf+4 now has more pushback on block
SS+2,3 window for hit confirming increased, CH (SS+2),3 now shifts to d/f+3 style AT
SS+2,1+2,1+2 tackle speed increased
WS+1,3 no longer KNDs, instead is +frames on hit and safe on block
WS+3 is now safe on block and CH WS+3 now sends the opponent into a rolling state
WS+4 has a new animation and leaves Dragunov closer to the opponent in combos, creating new options mid-juggle
WR+2 animation has been redone, now launches the opponent for combo on NH
BT d+3 now KNDs on NH
New Moves
4,1 - New combo filler and punisher, gives Dragunov a scary i12, +8 on hit punisher
4,4 - "Safe" string that leaves the opponent recovering WS with Dragunov at +frames, launches on CH (4),4,
f+3,3 - Skip kick to d/f+3 style attack, jab punishable on block. NCc and shifts to d/f+3 AT at clean range.
f,f+3 - New massive, high "homing" kick. +frames on block, KND/W! on NH.
d+4,4 - A new consistent ender to combos, still hits l,h non-jailing
d/f+1+2 - Low attack reversal, incredibly large frame window, causes side swap with opponent
d/f+1,4 - Extension to Dragunov's d/f+1, NCc string that KNDs the opponent for small combo/oki
qcf+1 - New launcher, hits high, safe on block. A much needed change to Dragunov's DR MO of unsafe attacks.
FCD 1+2~1+2 - Tackle extension to Dragunov's "living dead", a fan request from DR
WR+3 - Running slide (low) that shifts to an attack throw on NH, cannot be performed as iWR+3
Tekken 6.0 to Tekken BR
3,1,2 hit box improved, now a more consistent finisher when tagged onto the end of combos
4,1 no longer works on all axes during combos, only on-axis and slightly off-axis
qcf+1 hit box improved drastically, no longer phantom whiffs on certain characters
b+3 has been completely reworked, no longer launches on CH
u/f+3+4 speed increased slightly, recovers faster on successful grab to guarantee d+3 follow up for additional damage
d/f+1+2 reversal window has been drastically reduced, now requires much more accurate timing
WS+1,3 is back to its DR properties, once again KND/W! on hit and unsafe on block
WS+2 now flips the opponent mid-air requiring new follow ups to combo, surprisingly this increases its damage potential
WR+2 no longer launches on NH, now requires CH to launch
New Moves:
f+3,2 - Skip kick to right palm, hits m,h non-jailing, safe on block, CH (f+3),2 KNDs the opponent
f+4,4,3 - New extension to f+4,4, gives Dragunov more consistent air combos and wall carry
b+3 - i14 high "homing" attack, no special properties on NH/CH, safe on block
qcf+3 - Dragunov performs a slide similar to WR+3 but only shifts to AT on CH
Tekken BR to TTT2
4,1 once again works on all axes, though when hitting BT might push the opponent too far to combo
CH (4),3 now sparks on hit, as a result CH 4,3, d+3+4 damage increased drastically
b+1 has been changed to u/f+1, now a different stun leading to a guaranteed follow up on CH
d+2 now crushes some mids on active frames as well as recovery
d+4,4 now requires a substantial deep dash to finish with on long combos, similarly to 3,1,2
d/f+1,4 no longer leaves the opponent next to you for small combo, instead KND/W! to Dragunov's right
d/f+2 hit box has been fixed to hit moves such as Lars' u/f+3 on block
WS+2 has been reverted to its DR self, it no longer flips the opponent mid-air
CD can now be cancelled by tapping up
New Moves:
WS+1,2 - New extension to WS+1 similar to Dragunov's WS+1,3 in Tekken 6.0, hits m,h non-jailing
b+1,2 - New poke string for Dragunov, first hit is safe and has a few high crush frames, second hit KND/W! on CH
1+2,1+2 - Homing attack to tackle extension, can still be escaped or reversed on hit
1+2,4 - NC KND/W! string that starts as a homing attack, safe on block, but hits m,h non-jailing
f+3~d/f - Dragunov's f+3 to CD, follow ups are identical to Dragunov's standard CD options
Bread and Butter combos:
Tekken DR (The age of d+4,4)
d/f+2, 2,1,3, d+4,1,3
WS+2, 2,1,3, d+4,1,3
qcf+1, does not exist yet
qcf+2, u/f+4, d+4,4, d+4,1,3
qcb+2, f+4, d+4,4, d+4,1,3
u/f+4, SSR, d+4,4, d+4,1,3
f+1+2, does not launch yet
Tekken 6.0 (The age of creativity)
d/f+2, 4,1, 1, 1,3,2, B!, f,f, 3,1,2
WS+2, 4,1, 1, 1,3,2, B!, f,f, 3,1,2
qcf+1, b+1+2, B!, SSL, 3,1, 4,1, d+4,4
qcf+2, f+2,4, f,f, 1, 1,3,2, B!, f,f, 3,1,2
qcb+2, 4,1, 1, 1,3,2, B!, f,f, 3,1,2
u/f+4, d+4,1,3
f+1+2, f,f, b+2,1, 1,3,2, B!, f,f, 3,1,2
Tekken BR (The age of f+4,4,3)
d/f+2, f+4,4,3, 1, f,f+2, B!, f,f, 3,1,2
WS+2, b+4,3, 1,3,2, B!, f,f, 3,1,2
qcf+1, f+4,4,3, 1, f,f+2, B!, f,f, 3,1,2
qcf+2, f+2,4, f,f, 1, 1,3,2, B!, f,f, 3,1,2
qcb+2, f+4,4,3, 1, f,f+2, B!, f,f, 3,1,2
u/f+4, d+4,1,3
f+1+2, f,f, b+2,1, 1,3,2, B!, f,f, 3,1,2
Unique properties/bugs/strings that don't exist in the future version of the game
Tekken DR
CH f,f+2, d/b+2,1,2, d+4,1,3 deals tremendous damage
f+2+3 leaves you at slightly different axes post grab (PSP vs Arcade/Online edition)
f,f+3 (despite being a kick) can be punch parried
CH (d+4),4,3 - Hit confirmable string that KND/W!
u/f+4 leads to a decent damage combo with respectable carry
Tekken 6.0
2,1,3 is the ender of choice for carrying without using B!, requires a quick dash to fully land all hits (e.g. d/f+2, 4,1, 1, 1, dash in, 2,1,3)
3,1,<2 tracks 360° on grounded crossover
(4),1 hit box low crushes on active frames
iWR+2 launches for full combo on NH, this is the first and last game where this is the case
Tekken BR
WS+2 flips over the opponent mid-air requiring special follow ups, this is the first and last game where this is the case
qcf+3 does not high crush on startup but is considered airborne, crushes highs before impact frames, crushes many mids on recovery