Ness ranks 9th on SSB's tier list for a predictable and at times unreliable recovery, which many foes use to their advantage, as well as some range issues. However, he does have a decent amount of combos, due to the aforementioned double jump cancel.
 How to unlock Ness
To unlock Ness, play 1-Player mode in Normal with 3 Lives without continuing, then defeat Ness in a match. He is fought on Dream Land.
Ness is a fairly small, medium-lightweight character with very high damage attacks. His greatest metagame comes from his air game. He has the game's lowest double jump cancel, which can be used to perform devastating combos, and a quick meteor smash in his down aerial as a finisher to many of them (example here). Ness's special moves serve a variety of purposes; his neutral and up specials (PK Fire and PK Thunder respectively) are projectiles, and his down special (PSI Magnet) can absorb energy projectiles such as Fireballs or Charge Shots and recover some of his damage. This can be used to his advantage in doubles - when the opponents are unable to do anything (usually during the time they are KO'd), a partner Pikachu, Fox, Mario, or Samus can repeatedly fire projectiles at PSI Magnet to recover Ness's damage. In addition, Ness possesses some of the most powerful throws in the game, and if followed up with edgeguarding, it can be extremely difficult for characters with poor recoveries such as Link and Samus to recover. However, his special moves are slow to execute. Ness himself is somewhat slow normally, but his fast roll and certain advanced techniques can help this problem. Perhaps his greatest disadvantage is his overall poor range, which can severely limit his otherwise excellent combo ability.
Ness's recovery, distance-wise, is one of the greatest in the game due to PK Thunder 2's sending him a very far distance, coupled with his large double jump (second only to Yoshi), with its maneuverability also making it difficult to attack Ness out of it. However, he is disadvantaged by the fact that PK Thunder 2 is easy to gimp, due to taking some time to complete and having to go in a semicircle around Ness - if anyone touches the thunderbolt, Ness will become helpless instantly. Even projectiles such as Pikachu's Thunder Jolt and Fox's Blaster can gimp the move easily. A "solution" to this, used by many Ness players, is to use the double jump away from the stage, and then use PK Thunder. At this distance, it is difficult for most of the cast to follow up with an edgeguard, as it will likely be too far for them to recover, resulting in a SD for them. However, even then, there are a few characters who can recover from that distance, such as Kirby, Pikachu, or another Ness.
On a competitive level, Ness was originally rather dominant, being ranked 3rd in the S tier on the first well-known Super Smash Bros. tier list. In the second tier list, he dropped to 8th place, and dropped again on the third list. Theoretically, this is the largest tier drop of any character in the series. Ness's strong point are his excellent combos and air game, but his poor range gives him big problems facing excessive range such as Captain Falcon's up smash, or Kirby or Pikachu's up tilt. Ness's approach is also easily read, with his two projectiles being slow and predictable. Ness overall has below average matchups, with an especially terrible matchup against Pikachu, and only two advantageous matchups (against two bottom tier characters).
 In Competitive play
 Notable players
 Tier placement and history
Ness used to rank very high at 3rd place on the first SSB64 tier list only below Pikachu and Kirby. With double jump canceling, Ness was a dominant force in the SSB64 metagame, as his DJC'ed aerials can rack up a huge amount of damage, and Ness can perform deadly zero-to-death combos. Ness has became less effective as the metagame progressed however. His short range in his attacks made his DJC combos lose recognition and effectiveness, and Ness's recovery, despite covering a great distance, can be exploitable due to it being predictable. This causes Ness to drop from a top tier 3rd place to a low-mid tier 8th place by the second tier list and dropping again to 9th in the third tier list. This is also currently the proportionally largest tier list drop of any character in any Smash Bros. game.
 Double jump cancel
DJCing is a glitch-technique that can be used by Yoshi and Ness. It involves using an aerial just after starting a double jump. This cancels the momentum of the double jump and allows quicker aerials, while also being able to speed up short hops, making short hopped DJC'd aerials especially effective when Z-cancelled. It can also help with aerial combos.
 Double jump landing
Double jump landing (also dubbed the Nesslevator) allows Ness to cancel his air momentum with an aerial attack while horizontally moving in midair. This results in a quick and smooth landing back onto a platform akin to wavelanding in Melee.
 Double jump rushing
Albeit extremely difficult to do outside TAS, Ness can move incredibly quickly on the ground by cancelling multiple double jumps while moving horizontally. This is due to his second jump having very high horizontal movement during its initial frames. Demonstrative video here.
 Dash turnaround ledgegrab
Ness is the only character in the game along with Fox who can use the turnaround animation of his full sprint to grab a ledge. This is due to his turnaround animation changing the faced direction before the character "brakes".
 Edge sweetspotting
Along with Pikachu, Ness can sweetspot the ledge after he hits himself with his PK thunder if he grabs the ledge at the right angle and from the right distance.
 Special ledge cancel
Ness can grab the ledge while using his PK Thunder move or his PSI Magnet. This results in tougher edgeguarding from opponents. Also, these moves cancel his double jump, making them useful for ledge stalling or to refresh the invincibility frames granted by the ledge.
Ness was a seemingly-average kid from Onett, but in truth, he was destined for much more. When a strange meteorite landed near his hometown, the little boy with psychic powers set out to save the world. Little has been said of Ness' character, and much remains hidden.