Semi-spike

The shaded angles considered to be semi-spikes.

An example of a semi-spike; the opponent is sent at an angle that is almost parallel to the ground.

A semi-spike or pseudo-spike is a type of attack that does not send the opponent directly downward, but instead in a mostly horizontal trajectory which (due to gravity) will quickly turn into a vertical trajectory. This is distinct from a meteor smash, which sends the enemy downwards without a prior horizontal trajectory. Semi-spikes are dangerous as they often leave targets below and away from the edge, one of the worst positions to recover from.

Characters who can semi-spike

The following is a list of moves that are considered semi-spikes in that they send targets at an angle 30 degrees away from horizontal. Moves with the Sakurai angle can also be considered semi-spikes at low knockbacks, but this is generally impractical and only useful at low damages.

Bowser

Bowser in SSBM can use:

Neutral attack - A small portion of the first claw swipe has an angle of 30.
Down smash - The first 6 hits are semi-spikes, though they cannot really be used as such because of the follow-up hits.
Back aerial (Super Smash Bros. Melee only) - Has semi-spike properties, but high ending lag combined with Bowser's poor vertical recovery make it a very risky edge-guarding manoeuvre. His back aerial gained more power and became less risky in Brawl, but lost its semi-spike properties (now having an angle of 35).
Down aerial (landing hit)

Captain Falcon

Captain Falcon in all three games can use:

Up aerial - The hitbox at his foot at the end of the animation semi-spikes opponents. It is less effective then Ganondorf's up aerial.

Diddy Kong

In Diddy Kong's debut, his semi spikes include:

Forward smash (first hit in close)
Monkey Flip - using the move against enemies in the Subspace Emissary makes it a semi-spike.
Rocketbarrel Barrage - ramming into opponents is a semi-spike.

Donkey Kong

Donkey Kong can use his cargo throw in all three games, but gained a semi-spike in Brawl with his Final Smash.

Cargo down throw
Konga Beat (weak waves)

Dr. Mario

Dr. Mario has a semi-spike in Melee, but his clone Mario does not have one in this game.

Back aerial - Dr. Mario can attack with this twice and still recover, despite his poor horizontal recovery.

Fox

Fox is famous for introducing the "Shine spike" technique in regards to edgeguarding with Semi-spikes.

Down smash - It is very fast with good power and decent reach. It can be very effective if landed near the edge. It has noticeable ending lag however, and its edgeguarding capabilities are rather limited.
Reflector - Has set knockback in Melee. It has set knockback properties in Brawl, but once the opponent approaches 100%, it hits with increasing knockback. Much more effective on characters with poor recoveries.

Falco

Down smash - Similar to Fox's down smash, except Falco's down smash has slightly less power and slightly less ending lag.

Ganondorf

Ganondorf has access to a Semi-spike similar to Captain Falcon's, and got an addition one in SSBB.

Up aerial - The hitbox at his foot at the end of the animation semi-spikes opponents. It is stronger and produces more hitstun than Captain Falcon's up aerial. It is one of the best and most known semi-spikes in both Melee and Brawl, it complements Ganondorf's already deadly edgeguard game.
Forward tilt (Brawl only) - It is the second strongest semi-spike in Brawl, but its poor vertical reach limits its edgeguard capabilities. Still, with its fast start-up it's great when used near the edges for KOing.

Giga Bowser

Down smash (first 7 hits)
Back air - Retains its semi-spike angle in Brawl.

Jigglypuff

Jigglypuff can utilize these Semi-spikes in Brawl.

Down smash - Low start-up lag and good power for a semi-spike. It has noticeable ending lag and very short reach, Jigglypuff is better off using its WoP for edgeguarding.
Down aerial - If it is sourspotted, the move can semi-spike.
Final Smash - When shrinking down to her size, if opponents hit her while she's shrinking, it's a OHKO semi-spike.

Kirby

Down smash - When sourspotted, it semi-spikes the opponent with decent knockback. To sourspot, Kirby has to hit the opponent with tips of his feet. It has decent reach and fast startup, so it is usable for edgeguarding.
Aerial Hammer (Brawl Only/second swing) - A very powerful semi-spike, it is the second strongest semi-spike at low percentages and the third strongest at high percentages (above 150%). However, landing it is very difficult since Kirby has to the land the second hit, not the first hit and both strikes have noticeable start-up lag. If Kirby does land the second hit on a recovering opponent, it usually results in a KO.
Stone - Side hitboxes have semi-spike abilities with decent power. Good to use on opponents on the edge.
Forward smash - While tilting the joystick downwards. The trajectory of the attack is low enough that some characters have a very hard time recovering, such as Ike or Link. A decent semi-spike at mid-high percentages.

Link

Link has access to a few Semi-spikes, but notably less than his Toon Link incarnation.

Neutral attack (third hit).
Up throw (only to bystanders).
Spin Attack (Melee NTSC versions only) - Hitting someone with it after the initial hitbox semi-spikes the opponent. Very powerful, fast, and good reach, it could be considered the best semi-spike in Melee (on par with Sheik's forward aerial).

Lucas

Down tilt - Similar to Ness's down tilt, but is slightly stronger (still can't KO at 999%, however). It is impratical for edgeguarding as it has very short reach and produces no knockback at realistic percentages.

Luigi

Luigi Cyclone (first hit) - Weak and impractical, but still a semi-spike.

Mario

Mario has a single attack in SSB that can Semi-spike.

Forward aerial - Does a forward drill kick. Last few hitboxes can semi-spike.

Marth

Down tilt - When tipped, it semi-spikes the opponent. Fast, good reach, and decent power makes this a effective edgeguarder, especially against those who try sweetspotting the edge. It is even faster in Brawl, and does not need to tipped, but shorter reach and Brawl's physics make it less effective.

Meta Knight

Down aerial - Very fast and has almost no ending lag, Meta Knight can WoP opponents with his down aerial. This, combined with its decent power and Meta Knight's multiple jumps, make it arguably the best semi-spike in Brawl, if not, the most versatile. The weaker part of the attack is not a semi-spike (its angle is 35).
Aerial Shuttle Loop - Has very high base knockback but very low knockback scaling. Almost no start-up lag and very strong initial knockback makes it arguably the deadliest semi-spike in Brawl. It's also great for stage-spiking. Excellent anti-edgeguard maneuver, this move is the primary reason Meta Knight is arguably the riskiest character to edgeguard, as characters risk being semi-spiked away from the stage in attempting to edgeguard Meta Knight. It is a very effective edgeguarder, but is risky since it leaves Meta Knight in a helpless state after the move is finished. Most effective at edgeguarding opponents recovering from above, due to the nature of the attack and being less risky.

Mewtwo

Disable - In the air, this move can semi-spike.

Mr. Game & Watch

Down tilt (Brawl only) - Has set knockback properties. It is effective at edgeguarding as it is fast, has good reach, and has a long-lasting hitbox.
Sourspotted down smash - It is fast, powerful, and has good reach, it is very effective at edgeguarding. Even though its sweetspot sends opponents vertically, it is still effective at edgeguarding given its powerful sweetspot.
Chef - Semi-spikes opponents who make contact with the frying pan with low power. It is not effective as a edgeguarder due to its short reach and slow start-up lag.
A 6 with Judge - Semi-spikes opponents with good power accompany by fire damage. It is noticeable for being the only other Judge other than #9 that is actually useful. It is deadly to recovering opponents.

Ness

Down tilt (Brawl only) - It is a semi-spike but a very weak one. Only noticeable at extreme percentages. It is impractical for edgeguarding as it has very short reach and produces no knockback at realistic percentages.
Dash attack - It semi-spikes if this attack sends opponent horizontally.

Peach

Forward smash (tennis racket) - When sweetspotted in Brawl, it is the strongest semi-spike in the game. Otherwise, it is weak. It is unreliable for edgeguarding due to its short reach and random nature but is potentially deadly.
Down smash (Melee Only) - When fully charged, it is the strongest semi-spike in Melee, if multiple hits connect. Her down smash is strong enough to KO opponents at low percentage as 20%. However, her down smash is less effective if the opponent is above 100%.
Peach Bomber
Vegetables

Pichu

Down smash - Hits opponents in the opposite direction with his head.
Down tilt - Hits opponents with its tail, good for Edge-guarding.

Pikachu

Up aerial - It semi-spikes somewhat weakly if the player connects the tip of Pikachu's tail but it is fast.

Samus

Bomb - A weak semi-spike. However, the hitstun can be used to pull off gimps on characters with poor recoveries.

Sheik

Sheik is notable for having one of the best semi-spikes in Melee.

Forward aerial - Sheik quickly swipes her hand in front of her, semi-spiking the opponent. Extremely fast and powerful, it was the most well-known and feared semi-spike in Melee, despite its short reach and short-lasting hitbox (it is on par with Link's up special move for being the best semi-spike in Melee). It still semi-spikes in Brawl, but was weakened significantly.
Final Smash - As this is a Final Smash, it cannot be used in tournaments.

Toon Link

Forward tilt
Dash attack - Fast and good reach, but it is very weak and the semi-spike is only noticeable at very high percentages.
Down smash - The first strike is a semi-spike with high base knockback but the second strike is often landed afterward which has vertical knockback instead. At very low percentages, the much higher base knockback of the first strike can override the knockback of the second strike and results in a surprisingly powerful semi-spike that may even KO depending on the location and character it was landed on.
Forward smash - A small amount of the first swing has an angle of 10 degrees.
Down air (landing) - Both the wind and the impact of landing are semi-spikes.
Back throw
Up throw (only to bystanders)
Spin Attack - the multi-hits are semi-spikes, though they exist only to suck in targets for the rest of the attack.

Wario

Down smash
Back throw (only to bystanders)
Slow edge attack
Wario Bike (wheelie)

Wario-Man

Down tilt - Very fast and powerful.
Down smash
Forward throw
Back throw (only to bystanders)
Slow edge attack
Wario Bike (wheelie)
Wario Waft (fully charged)

Wolf

Down throw - A throw that semi-spikes opponents with surprisingly high knockback scaling. It can be very deadly if Wolf grabs the opponent on the edge as the throw has bizarre properties that negates the opponent's momentum, thus making it very difficult for some characters to recover.
Forward smash - First hit only, it is extremely weak and only noticeable at extreme percentages.
Blaster (melee portion only) - The melee hitbox of the blaster produces a weak semi-spike but the opponent is almost always hit with the projectile afterward, thus cancelling out the knockback of the first hit.
Reflector

Yoshi

Down tilt - It has set knockback in both Melee and set knockback properties in Brawl. It is fast and has decent reach and can be useful for edgeguarding. More useful in Melee than it is in Brawl.
Down smash
Egg Lay - using the move against enemies in the Subspace Emissary makes it a semi-spike.

Zelda

Up smash - Parts of the first hits act as semi-spikes, though the minimal SDI capacity makes it difficult for it to be a deciding blow.
Down smash - Very fast and it has good power for a semi-spike. It's short reach limits its edgeguard capabilities but can still be effective. Much stronger in Brawl than it is in Melee.
Forward smash - Like the up smash, parts of the first hits act as semi-spikes to keep targets trapped in the attack.
Neutral air - Same as the up and forward smashes.
Nayru's Love (first five hits)

Other

Hitting someone with a thrown Star Rod.
Porygon 2's attack launches opponents on a semi-spike trajectory very powerfully. It was by far the strongest semi-spike in Melee, KOing anybody with at least 25% damage.
Suicune's Aurora Beam (Brawl only) is a semi-spike that OHKOs any opponent. When considering items, this is by far the most powerful semi-spike in Brawl.
In Melee and Brawl, Master Hand's open hand crush has two hitboxes; if the player is hit by his palm, they will be sent horizontally on a semi-spike trajectory with powerful knockback. If the player is just outside his palm, it instead results in considerable vertical knockback. Crazy Hand has a similar attack, though it is weaker and deals 10% less damage.
If the opponent is grabbed by the player and the another opponent attacks the player that grabs the opponent, the opponent that was being grabbed will be sent horizontally on a semi-spike trajectory.