Latias & Latios

The pair fly in one after another, unleashing attacks as their paths cross. The air pressure generated by these two creates wind currents that affect items and fighters. Latias (, Latias) and Latios (, Latios) are creatures in the franchise. They appear starting in Super Smash Bros. Brawl as a 2-in-1 Poké Ball Pokémon.

Origin
Latias and Latios are a pair of dual /-type introduced in in. Latias and Latios are categorized within the Pokédex as the "Eon Pokémon" at #380 and #381 respectively. In Pokémon Ruby, Sapphire, and Emerald, one of them, depending on the version for Ruby and Sapphire or the player's choice for Emerald, appears randomly in the wild after beating the Pokémon League roaming the region and attempting to flee after each encounter, while the other can be found in the event-only. Both make a return in the remakes , where, depending on the version, one of the pair requests the player and to save the other in Southern Island from  (Omega Ruby) or  (Alpha Sapphire). After defeating the villainous team, Latios (Omega Ruby) or Latias (Alpha Sapphire) will join the player's team. Both of them are capable for.

is a -type physical move with 70 base power and 90% accuracy which has a 10% chance of raising the user's Defense by one level. It is available as a TM or a tutor move to several Flying-type or bird-like Pokémon, including Latias and Latios.

As Poké Ball Pokémon
Latias and Latios appear in Super Smash Bros. Brawl as a 2-in-1 Poké Ball Pokémon, marking the first time two different species of Pokémon come out of one Poké Ball. Only one will come out, but both have the same outcome.

When summoned, both Latias and Latios scoot off in opposite directions (Latias will attack from the right, Latios from the left). They zoom back and cross paths in an X-fashion, similar to the Kat & Ana Assist Trophy; however, Kat & Ana cross at the same time, while Latias and Latios cross one at a time. The impact causes heavy damage, and knockback is rather strong. The winds from their speed pick up and affect items and characters, forming a sort of "vacuum" at their intersections. This can be extremely dangerous for light characters and those with poor recoveries because a player can easily get caught in a "vacuum" and get KO'd off the side or knocked too far away from the stage to recover. They do not harm the person who summoned them. Despite them being very rare in the Pokémon games (running from the player at every opportunity), they are treated as common Pokémon in Brawl.

Latias & Latios can be avoided by using a recovery move like 's or 's to hover around the upper blast line. Since Latias & Latios usually do their attack horizontally, the technique will usually work, but if the player starts to fall, they are likely to get hit.

As Poké Ball Pokémon
Latias and Latios return as Poké Ball Pokémon and are functionally identical to their Brawl version, but nerfed in both damage and knockback.

In Smash Tour
Latias and Latios appear as an item in Smash Tour: when used, they allow the user to team up with a chosen opponent during a battle.

As Poké Ball Pokémon
Latias and Latios return as a Poké Ball summon.

Spirit
Latias and Latios also appear together as a spirit.

Trivia

 * Unlike other Legendary Pokémon, the crowd does not gasp when Latias and Latios appear. Additionally, they have the standard frequency rate instead of the Legendary rate.
 * The setting of the duo's spirit battle, the gondola area of Delfino Plaza, is likely a reference to Alto Mare from the movie Pokémon Heroes, which heavily features the legendary dragon duo.