This is the Silver Age Flash and Kid Flash combo of Barry Allen and Wally West (green eyes, red hair). Very classic costumes. The Flash is shown with whited-out eyes which is a motif of the costume worn by Wally when he succeeded Barry as the Flash.

At SDCC Brandon Vietti described Kid Flash as

He is Wally West. He’s 15, he’s not as fast as the Flash. He has to accelerate and decelerate.

Kid Flash is voiced by Jason Spisak.

Kid Flash is Wally West. We haven’t seen his origin on-screen, but we can assume, based on the original comics chronicles, that Wally was a massive Flash fan and was over joyed at the opportunity to meet his hero in real life. However, at that exact moment a freak lightning bolt struck the Flash’s laboratory and recreated the exact accident that had given the Flash his powers. Wally gained the same power of superspeed and joined the Flash as his kid teenage sidekick. Kid Flash more than makes up for not quite being as fast as the Flash with a teenage enthusiasm and a more direct, less elegant approach to combat. The Flash is naturally gregarious and laid back, but Kid Flash (or just “Kid” as he gets called) tends to be more tightly wound and impatient.  Wally’s parent know about his secret life and seem to accept it, his mother once told him “Wally, you lead a very strange life, but we’re use to it. Largely.” (Young Justice (vol. 2) #0 (March 2011)).

Kid Flash was excited when he and three other sidekicks were told that they were to be inducted into the Justice League. On July 4th Kid Flash, Aqualad, Speedy, and Robin (Kid Flash’s best friend) were brought by their mentors to the Justice League’s Hall of Justice. They were given a tour, but that was it. Speedy was furious and revealed that Hall wasn’t even the League’s real headquarters – it was a false front designed to deflect attention from their real HQ in orbit. He accused the League of not treating them like equals and then stormed out. Kid Flash hadn’t expect anything more than the tour, but Speedy’s parting words stung “I guess they’re right about you, you’re not ready.”

Immediately afterwards the League received two emergency calls – one to a fire at Cadmus Labs and another to a supervillain attack by Wotan. The League were forced to ignore Cadmus and left to fight Wotan. Flash told them that they’d get a change to join the League when they were ready, but after he was gone Kid Flash railed that “When we’re ready! How are we ever supposed to be ready when they treat us like.. like sidekicks!” Robin suggested to Aqualad and Kid Flash that they investigate Cadmus on their own. They would solve the case first and prove to their mentors that they were ready for League membership. Kid Flash was naturally the first one there and saved a pair of scientists, but needed pulling to safety by Robin when he misjudged his step. And again, once inside Cadmus, he ran ahead of them and nearly collided with a contingent of gene-trolls.

The three sidekicks eventually liberated Superboy, a clone of Superman created as a weapon by Cadmus, and escaped with him to the surface. However, their way was blocked by Mark Desmond, Cadmus’s chief scientist, who had transformed himself into the Blockbuster to stop them escaping. As Kid Flash and co pulled themselves out of the rubble they found themselves face to face with the full Justice League and a very unamused Batman who told them “you will not be doing this again!”  They protested that they’d become an effective team and Kid Flash pointedly included Superboy in that description (“Independence Day”, “Fireworks”).

Superboy went to stay with Kid Flash in Central City while Batman considered that to do with the new team. Wally introduced Superboy to pizza and watching TV, but his mother turfed them out after two days and told them to find something more productive to do. Wally took Superboy to the mall clothes shopping on the Batman’s expense card, but they ran into the Terror Twins and fought to protect their civilians and their secret identities until the Flash and Superboy scared the Twins off (Young Justice (vol. 2) #0 (March 2011)). The next day Batman told them his decision. They were to become a new covert branch of the Justice League dedicated to the type of low-key undercover mission that was now impossible for the high-profile adult Leaguers (“Fireworks”).

One benefit to the new team that Kid Flash instantly picked on up was the presence of Miss Martian (Megan), the Martian Manhunter’s niece. Robin was Kid Flash’s best friend, but the two friends were strongly competitive and Robin repeatedly deflated Wally’s clumsy attempts to flirt with Miss Martian (“Fast with his feet, not so fast with his mouth.”). Wally retaliated by making a point of revealing his secret identity to his other team-mates – something Batman had forbidden Robin from doing (“Welcome to Happy Harbor”). They were on a mission to Santa Prisca when their friendly banter turned serious. Robin presumed that his experience and association with Batman automatically made him the group’s leader, but Kid Flash put him down saying “Dude, you’re a thirteen year-old kid who ducked out on us without a word.” Their bickering amused the bad-guys, but wasn’t settled until they were both made to realise that it was Aqualad who had led them all along (“Drop-Zone”).

Kid Flash possesses the power of superspeed. He is capable of out running most vehicles and acting faster that almost anybody else. He is, however, not as fast or as experienced as the Flash – it takes him longer to accelerate and decelerate and he has yet to learn the technique by which the Flash can vibrate his molecules through solid objects. A side effect of Wally’s speed is his super fast metabolism, this leads to him having to eat more often than normal people and it’s not unusual for him to be tucking into a burnt cookie or a bag of chips whilst everybody else is talking.

Kid Flash’s costume is padded to protect him from being injured from collisions with bad guys at super speed (one of his favourite manoeuvres). His costume’s bright primary colours can be darkened in a moment should stealth become necessary. Kid Flash also wears a pair of goggles that protects his eyes while moving at superspeed and allow him to see in the infrared.

Although he doesn’t always show it Wally is a science prodigy (Cartoon Network website).