All of Koishi's moves except for her light attacks (melee and projectile) have a delay until they are used. Using a heavy melee, heavy projectile, or special attack makes a corresponding icon next to her spirit gauge light up (red for melee, blue for ranged, green for special). The icon will blink for a couple seconds; once it stops blinking, it will trigger after certain things happen:
- Heavy Melee Attacks trigger once the opponent comes within range (below you and a bit in front for her down attack, directly above you for her up attack, etc.). It's a bit situational, honestly, but can take the opponent by surprise due to its ability to trigger even when Koishi normally can't do such an attack (like when dashing).
- Heavy Projectile Attacks trigger when the opponent is at a certain angle from Koishi, depending on the direction inputted -- neutral, forward, or backward trigger when the opponent is level with Koishi, up and down trigger when the opponent is higher or lower than her (respectively). It directly targets the opponent's position, bypassing bullets and physical distance, and can trigger at any time so long as Koishi isn't already attacking, so it's great as a trap.
- Special Attacks vary depending on the attack. The grab attack triggers upon Koishi successfully landing an attack on the opponent. The corkscrew attack triggers when the opponent comes into range. The vine and rose-scattering attacks trigger after a certain time. The circle thingy and rotating laser activate when the opponent touches the glowing line.
Koishi strikes me as being excellent for mind games, because the opponent can't see exactly which moves have been set to trigger -- only whether it was melee, ranged, or special. Also, the fact that her moves can trigger at any time as long as she isn't already attacking allows you to set up bizarre combos that can catch the opponent off guard.
Of course, since she's vulnerable when she's attacking (particularly in the case of her heavy projectiles), being too predictable with her can allow the opponent to use her ability against her by deliberately triggering an attack and quickly dashing forward while she's vulnerable.
(Totally talking out my ass here, mind; I have no experience with human opponents)
E: Well, it took a helpful donation of a crummy FPS from Seriyu and hours and hours of hand-holding by Claxus et al in order to get my ports forwarded, but I managed to get on and play some Soku with others. Had a blast, thank you all, etc..