General Tactics
Psylocke has a fantastic, low to the ground wavedash. Flexible ground chains and an annoying fireball.
Team positioning
Point
Psylocke is capable on point as a standard, mobile rushdown.
Mid
You get to use her assist but her dhcs aren't strong enough to want to put her second.
Anchor
Psylocke's most comfortable place, where her AAA can be abused to the fullest.
Advanced
Dealing with snap-ins
As mentioned before, Psylocke is usually chosen for the use of her Anti-Air Assist, mainly with Magneto. If you are using MSP and are going against the same team, chances are your opponent will look for an opening to hit your point character and snap in your Psylocke, and eliminate Magneto and Storm's strong defensive options and reset possibilities.
If this is the case, there is very little Psylocke can do. Especially when coming in just after the snap-in. The most that can be done is to block Magneto's attacks and try to tech any throw attempts. Any counter attack attempt against Magneto will be extremely risky. If you do not have meter, you can try to pushblock to help get Magneto away from you so that you can super jump and build meter. Psylocke can jump two more times in succession while air borne. Magneto would either have to chase you, or wait for you to exhaust your all of your jumps and fall down. If you haven't built enough meter for a DHC, there are a few, risky options Psylocke can attempt to stop Magneto's attempts of attacking.
If you feel that Magneto will go for a ROM attempt, attacking with her jumping Roundhouse is a somewhat high priority move that can stop Magneto's light kicks if timed slightly later than when he first attacks. Psylocke can also use Roundhouse to stop Magneto's slide attempts or launchers.
If you feel like Magneto will call on a Anti-Air Assist, you can either shoot a Psy-Blast to slow the rate of the fall, or if you haven't used all 3 jumps, you can use a jump to bait out the assist, and then try to either out-prioritize or block Magneto's attack and once again try to super jump to build more meter.
It is recommended that once you have 2 meters, you use Psylocke's Kochou Gakure super, and DHC into either Storm's Hail Storm, or Magneto's Magnetic Tempest. If you end up DHCing into Magnetic Tempest, try to find a way to prevent the opponent from jumping over the rocks of Magneto's super so that he can't be punished. A rather effective way of preventing Magneto from being punished is to make sure the opponent blocks a few butterflies from Kochou Gakure, forcing them into into block stun and stopping any super jump attempts. It makes it even harder to punish if the opponent is in the air while blocking Psylocke's super, since it sends them down, and therefore they have to jump even later.
If your Magneto is snapped in, and you managed to build 2 or more bars of meter, again, try to find a way to DHC into the supers mentioned above. If you feel like you can score some damage, once you feel Magneto will rush in, or go for a triangle jump, the Psy-Blade attack will simply out prioritize any of Magneto's rush down options, and therefore you can cancel into Kochou Gakure, DHCed into Magnetic Tempest/Shockwave or Hail Storm. Any of the 3 options will lead into some hefty damage.
If your Psylocke is coming in while Storm is on screen, you have even fewer options, since Storm can just use her standing roundhouse (her launcher) to out prioritize any of Psylocke's air attacks. Furthermore, the fact that she has lighting attacks (that can, once again, out prioritize Psylocke's physical attacks) limits Psylocke's options even further. Psylocke's best bet is, just like against Magneto, to use her Kochou Gakure DHCed into Hail Storm and/or Magnetic Tempest/Shockwave. Psy-Blade will also out prioritize Storm's rushdown options just like Magneto.
Being the last character
Psylocke being the last character on a team isn't a good situation. She has no Tri-jumps, and any safe DHC options that came with Magneto and/or Storm being around are also gone. So anything like a Psy-Blade attempt will have to be a correct guess, because afterwords, she's left open.
One thing to keep in mind. If you have meter. Random snap-ins! Fast, high priority, and somewhat safe (while completely safe on block if not pushed blocked). This is really useful for double snap ins. And even if you feel that the opponent will not call out an assist, a successful snap-in is enough to temporarily break any momentum Magneto and/or Storm have. (Not to mention a chance to bring in their AAA and try to take it out)
If Psylocke is coming in against Sentinel, there is really nothing she can do. The most that can be done is hope that Sentinel will mistime the unblockable, or use her up+roundhouse flip kick to slightly raise her hit box.
If you are able to take the opponent down to their last character with Psylocke, depending on the character, she too can somewhat rushdown, even if it's somewhat one dimensional. Psy-Blasts mixed in with wavedashes can keep her on the opponent, even if she is push blocked. Try to mix up the constant barrage of pokes and Psy-Blasts with a throw attempt or two. Psylocke can also OTG with a Psy-Blast and follow up with wavedashing, being able to stay aggressive while building meter and slowly chipping away at their life.
