Anyone who has tried playing as Coral knows that she differs from the other characters heavily in difficulty of use. This guide will be a reference of tips/tricks I found help me to effectively use Coral( I have by no means mastered her, so if you feel something could use a revision or something needs adding please post a comment, also this is my first guide so bear with me)

Coral is last of the initially playable androids. She features and orange/blue colour scheme and in the battle with Embryo it is revealed she teaches kick boxing. She comes with a shotgun and a plasma field gun, and is currently the most advanced(difficult) character in the game.

Corals effective range is limited to about 3-4 body lengths from her, as her shotgun is extremely short range and her plasma field cannot be launched and has a radius similar to her shotgun. For these reasons I consider her to, for all intensive purposes to be a melee character, as you must be up close and personal to hit your target.

Shotgun:
Corals primary weapon the shotgun is a powerful short range spread weapon which fires in bursts. It boasts approximately a 45 degree firing arc in front of her which can be upgraded to about 60 at maximum power. It fires in bursts rather than continuously, which means you have to plan your play style around it and make good use of each shot as it takes about 1-2 seconds to reload after each shot.
Plasma field:
Corals secondary weapon is her plasma field gun which generates a plasma field at her present location, maxing out her cool down, however you do not have to be fully cooled down to use it again, but the less heat your gun has the longer the field will last. The field itself has multiple uses. Defensively it can be quite useful allowing the player to generate a barrier which repels projectiles and enemies, dealing damage in the progress, creating a temporary safe zone. I usually don't bother using defensively because generally your best defence is a good offense. Offensively the plasma field is also useful as it can be placed on mobs of enemies to soften them up, perhaps even killing them. I generally use it on large mobs of weaker enemies or to soften up larger ones for my shotgun.

Im going to list the items from most to least preferable and explain why.
1-Acceleration(Yellow Wings)
Acceleration is probably the best power up for Coral because it increases her ability to strafe and round up enemies exeptonaly, allowing her to get within effective range quicker and out of danger. Its also great for doing a hit and run with her plasma field.
2-Fire Power(Red Turret)
Fire power is second best mainly because it helps weaken groups before you hit them, as well as
giving her a ranged wepond. In addition its exeptinal in helping to maintain combos for longer periods of time when enemies are spread out.
3-Shut Down(Blue Lock)
Shut Down is not an ideal power up for Coral in my opinion because it prevents you from grouping enemies and makes it harder to get from one group to the next as they are no longer moving towards you. Great if you are about to die for a pause or if you are getting overwelmed however.

With both play styles you need to keep in mind that Coral is a melee character.
Primary: use when playing solo or in a group. Primarily you will want to play aggressively with Coral strafing enemies into groups large enough to make an effective shotgun blast, however do not be afraid to use it on singular enemies, just keep in mind that she is more efficient at tackling groups. When going to blast your target(s) get as close as you can safely, blast them and then back off while reloading, this ensures that as many of the bullets as possible will impact your target as they get less of a chance to spread out prior to impact. If you are attacking a large enemy then ensure you are point blank for your shot, her shotgun has a lot of damage potential, as long as every shot hits. Ensure that you take full advantage of her plasma field as it will help when dealing with large numbers of enemies or when cornered. Even just placing it in their path while strafing is a good use as enemies will not avoid it. When fighting bosses be sure to use your plasma field to deal damage to them in addition to shooting them.
Support: use only in a group, and only if the group needs a supporting member(all of mine do, most of the people I game with don't have a clue how to play so a support helps ensure success) . Coral is in my opinion a good option for a supporting character in a group setting as she is capable of tackling large mobs as well as creating safe zones for your allies with her plasma field. If you are playing competitively for higher score, do not play support as you are not likely to kill with any regularity to get a combo. Playing support is only useful when the other players are less experienced/skilled as mentioned earlier and only when the goal of beating the level is the primary objective. As a supporting character your job is to help ensure that other members of your team deal as much damage as possible. In order to ensure maximum damage you must prevent your allies from dying so they can achieve/maintain maximum level fire power. Coral is more than suited to this as power levels are not particularly important for her to be effective(kind of the difference between one shotgun blast in the face vs two, it makes no real difference other than you are more sure its dead), which means she can die and be less disadvantaged than other characters. Other ways she can ensure her allies remain alive is by proper use her shotgun and plasma field. When your allies are not in any immediate danger don't be afraid to blast a group of enemies, and if your allies are in need of assistance be sure to keep shooting, and attempt to use your plasma field to soften/breakup/create safe zone to save said ally.(this is a mostly hypothetical style as I haven't had much of a chance to play support yet, let me know if it works)

Got an example video (finaly) of me using Coral, first against Embryo(pardon the deaths, I lag while recording) and afterwards on the level Hive.
Embryo------
Hive----------