1 Meter: HP double > medium Ichi Ni San > HP double > medium Ichi Ni San > Shadow Flick Flack > Air Buster ender (57%)
2 Meter: HP double > medium Ichi Ni San > medium Ichi Ni San > Shadow Flick Flack > Shadow Flick Flack > Air Buster ender (65%)
( Damage calculation notes)
Notes: Her 2-meter punish uses her combo trait to do two Ichi Ni San linkers back-to-back, and the second shadow Flick Flack extends past the lockout window, but not long enough for the opponent to break three hits. Shadow Flick Flack hurts more than using the meter on the ender. Medium Ichi Ni San is fast enough to squeeze in the maximum amount of HP doubles, and does the most damage.
Flick Flack crushes lows, even though Orchid is doing a handstand and not off the ground, which makes it a good tool in close when your opponent is not in block stun. Blockade Runner is an extremely low profile slide attack that can duck under many projectiles and mid-range pokes; the HK version goes full screen but is -10 on block with some pushback that requires a calculated punish. Her staple opener is Ichi Ni San, a three-hit rekka move that requires three individual presses of a punch button. It has a low version (LP 3rd hit), overhead version (MP 3rd hit), and a potentially safe on block version that can be held in the opponent's face (HP 3rd hit). Max charge for the 3rd hit is unblockable, like threatening to hold and release one of Ryu's Denjin fireballs in SFV, and Orchid will recover in time to block jumps if the opponent holds up and Orchid releases quickly. Trying to shadow counter Ichi Ni San on the 3rd hit is very difficult, since Orchid can hold the HP 3rd hit past the brief shadow counter window and the MP overhead is naturally two hits already.
To make Ichi Ni San even stronger, the heavy version's third hit can be canceled into a forward dash while it is being charged. While the dash forward puts you at negative frames, it can be extremely risky for the defender to challenge with a button because Orchid can easily just delay the third hit slightly and release it, causing a counter hit. If you dash forward and catch your opponent by surprise, they might try to instinctively throw you. You can bait the throw by neutral jumping or doing the Whiplash overhead, which has some throw invulnerability and leads to a combo. To defend against Ichi Ni San, your best bet is to try and shadow counter the first or second hit after Orchid cancels a normal attack, or block and punish her light and medium strength mixups. If you block the heavy version's third hit, you will have to respect Orchid's block advantage. While only the third hit of these Ichi Ni San variations is an opener, the first and second hits can be canceled into shadow openers if you like.
Grenade and Orchid's instinct-only Firecats are mixup and pressure tools, so they are unlikely to be used as combo starters in the traditional sense. However, if you confirm that your opponent got hit by one of these tools during Orchid's pressure, linking a manual off these attacks will open a combo.
Orchid's linkers are the same as her openers. Blockade Runner is the highest damaging linker, while she can take advantage of her combo trait to string together back-to-back Ichi Ni San linkers if she chooses. Ichi Ni San when used as a linker animates like the 3rd hit in the opener version, so light linker is a 1-hit low, medium linker is a 2-hit overhead swing, and heavy linker is a 3-hit attack to the body. You can use these visual cues to help you combo break these attacks a little more easily than regular linkers. Flick Flack performs 2, 3, and 4 hits for light, medium, and heavy respectively, making it tricky to break for the uninitiated. Shadow Flick Flack is a high damage linker that hits with staggered timing, and the three combo breaker inputs must be staggered to match. If your opponent is uncomfortable breaking this shadow move, use it often to get lockouts, or free damage if they stop trying to break it.
Another way to break Shadow Flick Flack is to actually try to break the first, third, and fifth hits. The timing for doing this is deliberately slow and surprisingly regular, quite similar in timing to Jago's Shadow Laser Sword (in fact, almost identical to the frame once the freeze ends). If you're able to break Jago's Laser Sword consistently, try applying the same timing to Flick Flack and you might be surprised at how consistent the technique is. Once you prove you can consistently break Shadow Flick Flack, your opponent will have to begin counter breaking or else simply avoid using it for free damage.
Orchid doesn't have a battery ender, so she'll either choose to go for damage using her Air Buster uppercut or an ender that allows a setup. If you perform the Ichi Ni San ender, you can jump cancel the final hit and connect with an air throw. A mid-combo air throw does not recapture (only the opener version does). Instead, it will bounce the opponent off the ground and allow for a longer combo. You can choose to end the combo quickly and perform a setup; for example, hit the bouncing body with an attack like crouching HP, then cancel it into her Grenade. They will wake up into the ticking grenade and be forced to block your mixup or avoid it using some projectile invincible special move. If you'd like to try to extend your combo longer, you can jump cancel crouching HP and perform more attacks in the air (including more air throws), or cancel grounded normals into specials which will continue the juggle (for example, Flick Flack, which bounces an airborne opponent off the ground). Orchid can do some difficult to break juggle combos after her Ichi Ni San ender if you choose, but they are not mandatory to learn to be effective with Orchid.
Orchid calls a firecat with every press of HP+HK, including the press that activates instinct, as long as there is not one currently on the screen. They will run from off-screen behind Orchid towards the opponent, exploding on contact with waves of energy. If Orchid gets hit but has called a firecat, the opponent will get interrupted and Orchid can begin a combo. Firecats are very strong and thwart everything, including otherwise easy shadow counters and punishes on unsafe Blockade Runners or Air Busters, basically allowing Orchid to call repeated Marvel-style Plasma Beam assists during instinct. Orchid can do a full screen Blockade Runner to get in, and cover herself with a firecat at the same time. On block it will be safe because the firecat hits afterwards, and if Orchid trades, the firecat will continue on to hit the opponent. If she is able to corner you with instinct activated, you'll need to activate your best possible high-low defense and just hope you'll combo break when she finally hits you with repeated applications of her high-low mixup game. When combined with Grenade, her mixups become even more potent and dangerous, especially since there are extra visual effects on screen that can obscure Orchid's movement.