I was asked to post my meager knowledge about Juni, so here we go. If anyone else has anything to add, or if they find anything amiss, feel free to correct me and let me know.
Also, I have to note that this is covering A-ism. I know that V-ism is the most widely used, and I’ll be sure to add that info later, unless someone else puts it forth here beforehand.
Normals to keep in mind
s.MP - Her standing MP from afar, oddly enough, seems to work as a sufficient anti-air, so if your opponent jumps in deep, you can use this to push them back without too much worry.
c.MP - A nice poke to use, and it can be cancelled into her specials and supers as well.
s.HP - Not too much range, but it’s actually pretty quick to come out for a HP
attack when compared to most other characters, and it has pretty good priority.
I’ve seen it snuff out some things it shouldn’t have, either stopping them
completely or at the worst, trading hits with it. It also can be a killer on
your opponent’s guard gauge.
c.HP - Got an opponent that likes to toss out their air attacks from afar often so that they can nail you as they land at a safe enough distance? This is a
nice answer to it against most characters in that situation. Just remember only to use it against somewhat far ranged air attacks, because in close, it’s very likely it’ll miss altogether.
s.MK - It has decent enough range and height to serve as a good corner pressure move for those times you want to keep your opponent locked down. If you can anticipate a jump attempt to escape the corner, toss this out to stop them in their tracks. Just be careful of Shoryuken-type moves and supers.
j.MK - You want to use this to stuff out your opponent when they jump. Put it out there as you rise up toward them in midair, while they’re above you, since
its angle makes it a difficult move to land on an opponent underneath you or
completely grounded. Contrary to the way it looks, this is not a viable
cross-up move at all, as only the front leg will make contact.
c.MK - A really nice poking move to use. This has about as much range as her c.HK, but it’s faster to come out, so it can beat out other characters’
crouching attacks often.
s.HK - The same normal that Cammy is notorious for, and for good reason.
This has about the same properties, such as working well as an anti-air
against far jumping attacks or keeping up a bit of pressure on an opponent,
and it comes out damned fast for an attack of its type, so don’t be afraid
to send this out unless your opponent has meter, at which point, stick to
using it for pressuring, counterattacking and the like.
j.HK - It’s good when you’re coming in for rushdown purposes, but it’s a
GREAT air-to-air attack. Use it when you and your opponent are both airborne
coming in at around the same height. Nine times out of ten, you can beat
them out. Otherwise, this should probably be your main attack as you come in,
since while her j.HP has about the same priority, it has less reach, and
retracts far too quickly, meaning you’d have to jump in deep to do anything
useful with it half the time.
Overhead: f+MK - I wouldn’t have even bothered to mention this had I not
noticed anything about it that I felt was particularly noteworthy. It’s fairly
fast for an overhead attack and deals two hits, one of which is a nice height
off the ground. I’ve seen it stop some characters’ air attacks. It also starts
out with Juni quickly crouching low to the ground and rising, so timed well
enough, it can indeed save you from some of your opponent’s normals while
dealing damage.
Special Moves
Cannon Spike: Charge d, u+K
This is the same as Cammy and Juli’s Spike moves, and that includes the move’s
priority and such as well. The big difference, of course, is that Juni’s Spike
is a charge motion, and as such, pulling this out on your opponent suddenly is
an almost non-existant tactic with Juni, since any opponent worth their salt
will more likely than not be expecting the charge. Still, it’s to be noted that
it DOES make a good anti-air, so the same warnings or Cammy and Juli apply,
those being that you are advised to use the LK version so long as you can help
it, since missing the move in its MK or HK version does nothing but leave you
open for pretty much any punishment your opponent can dish out.
Spiral Arrow: Charge b, f+k; can be done in air
This is the same as Cammy’s, so as you would use Cammy’s, try to make this hit
with the last inch of the move so that you’ll be relatively safe as the move
ends. Otherwise, you’re asking for trouble. You can also use it to get
underneath projectiles as well, so if your opponent is a fair distance away,
slip underneath and take them down with a well-timed Spiral Arrow. One HUGE
difference from Cammy’s Spiral Arrow, though, is that Juni can actually do her
Spiral Arrow in the air (done by charging b, f+K before reaching the peak of
your jump). While Juni is airborne with this, she goes a good distance across
the screen towards your opponent, making it a really useful tool for getting
over projectiles or intercepting an unsuspecting opponent. Also, you don’t have
the recovery time from the slide from the grounded version to worry about,
whether it’s guarded or not, and if it is, against most characters, she stays
relatively safe, since she bounces back a decent distance. Definitely something
to keep your opponent on edge.
Hooligan Combination: hcf, u/f+P
Now, this move is EXACTLY like Cammy’s, right down to the execution. You can
follow up with a grab with f+K when you get in close which changes depending
on your height in relation to the enemy’s body or you can execute a sliding
kick by pressing nothing after the initial input. You can also press K to
cancel the move and land on your feet. While this move can be useful for
getting over projectiles, it’s all a matter of timing, since the move has slow
startup as it is, and even then, I myself would use it sparingly because you
can’t guard during the move, even when you cancel it to land on your feet. In
essence, you become a flying bullseye, especially to anti-air lovers, who’d
have a field day smacking her out of it.
Cannon Strike: qcf+K in the air during a forward jump
A diving kick that’s only as useful as you make it. Juni drops straight back
down towards the ground with this. The distance she drops is determined by the
strength of the kick button you press. Doesn’t have good enough priority to
contend with anti-airs, but it can definitely make a projectile happy opponent
sweat since you can use this to easily get in their face before their fireball
animation ends. Hitting this deep also makes for a nice starter for mixup
mindgames. Careful, though, because she’ll rebound if it’s blocked, similarly
to her Cannon Spike rebound, but higher so since the move starts in
midair…lots more punishment time for your opponent.
Mach Slide: qcf+K
One of the unique moves in Juni’s aresenal. The strength of the kick button
used changes how far the teleport takes you, and while you are invincible
during the teleport up until the point Juni reappears, if your opponent
anticipates it, you’ll get tossed or worse. A good way to use it (aside from
escaping/evading moves/projectiles) would be to throw off your opponent during
a rushdown. If, for example, you get your opponent to expect her Spiral Arrow
after you come in with a couple of attacks, you can do this to catch them off
guard for a throw (preferably her Earth Direct) or perhaps a super move. You can also chain this into her normals for mixups. The LK version can be used to blow the recovery off of a blocked heavy strike, so long as you don’t become predictable with doing it.
Earth Direct: 360+P
As with the other 360 grabs in the game, the range and strength change with the
strength of the punch button pressed. LP gives the most range, but is weakest,
while HP gives the least range and is strongest. Good times to use this one
are…well, any times that you know you can land a grab without fail, if you’re
decent at the 360 motion, but otherwise, good opportunities present themselves
after landing deep Cannon Strikes or getting in your opponent’s face with
cancelled Hooligan Combinations and Mach Slides.
Psycho Shield: f+PPP after guarding an opponent’s attack
Exactly like in the vs. games, Juni pushes her opponent back…WAY back. Almost
across the entire screen back, in fact. With this, Juni should never be much of
a victim to rushdown games, let alone being guard crushed. Get it down as best
you can and it’ll make Juni a lot more bothersome to deal with for your
opponents.
Super Moves
Spin Drive Smasher: Charge db, df, db, uf+K
Despite the more complicated motion, this is the same as Cammy’s and Juli’s
moves of the same name, with the same priority, as well as the same drawbacks
that said move suffers from, such as being highly punishable if blocked. It can
still be used for combos with Juni, but because of the move’s execution, her
combos tend to be far more specific and situational in nature. Be careful. Use
this one pretty much only when you know for sure you’ll connect with it.
Psycho Streak: Charge b, f, b, f+P
Juni summons Bison who executes a Psycho Crusher on the opponent. This is
basically her super projectile, though it emanates from a ways in front of her
instead of close to her, meaning that if your opponent is near enough to you,
they can do whatever to make you pay for the mistake of having used it, and
what’s worse, they have plenty of time to do so, since she stands there
saluting for about another second or so after Bison’s left the screen. So,
where are the good points in this move? As stated, it’s basically her super
projectile, meaning it will snuff out your opponent’s projectiles, with
stronger levels of it able to get through some super projectiles other
characters may send your way. It also can’t be blocked in the air, so thanks to
the speed at which Bison actually comes out and flies forward, it’s great to
use when your opponent decides to jump back to try and get some space.
Mixups
One nice thing that sets Juni apart from Juli and Cammy is the fact she has
more options to fall back on than they do.
Some things to do, for example, are jumping in with a HK and landing with a
c.MP, then going into a Spiral Arrow. Once your opponent starts to expect that, instead of doing another Arrow, go into a Mach Slide to get in their face to catch them with a throw, if they’re unsuspecting. Said time is a great opportunity for an Earth Direct.
Another big thing to keep in mind with Juni is the invincibility of her Mach
Slides. Provided you don’t become predictable with them, and your timing is
decent enough, you can bait your opponent into doing a move, then Mach Slide
through it, right into their face for some punishment.
The midair Spiral Arrow will have anyone on their toes wary about traversing the air to reach you, so if possible, try to keep it charged so you’ll almost always have it ready for use as they lift off.
Combos
due to the nature of the execution of her techniques, Juni’s combos are rather limited. Still, keeping what she can do in note is all the better for you.
j.HK, c.MP xx Spiral Arrow - Be careful when using this one, because against
some characters, the Spiral Arrow won’t come out fast enough to combo.
j.HK, c.MP xx Cannon Spike - Not much to say about this one, except that hitting
it makes for a good setup for a Psycho Streak if you can anticipate your
opponent trying to recover.
j.HK, c.MP xx Spin Drive Smasher - Similar to the combo dealing with the Spiral
Arrow, except you can have a level 2 or 3 to use in place to extend the reach
of the first part of it to connect more easily.
j.HK, s.HP xx Psycho Streak - This one is, of course, exclusive to Juni. Bison
comes out quite a ways in front of her, so the Psycho Streak can hit an
opponent from the distance the s.HP will knock your opponent.