Every member of Team Avatar deconstructs Free-Range Children; the reason why a bunch of preteen and teenaged kids can travel around the world all by themselves is because all of their parents are either dead, abusive, or busy fighting in the war. They all are also Child Soldiers, whether or not they have Elemental Powers, because the series takes place during a century-long global war and they have to know how to fight to survive the hundreds of combat situations they're forced into. They also have to know how to fight since their ultimate goal is to end the Hundred-Year War, and because Fire Lord Ozai has made it clear he won't end his reign of terror on the world they have no choice but to use violence to take him down.
Roku's portrayal in The Promise deconstructs the Spirit Advisor trope. Roku is well-intentioned in his advice to Aang to strike down Zuko before his withdrawal of support for the Harmony Restoration Movement triggers another world war. However, he is a. poorly equipped to handle the increasingly complex issues of the modern world, and b. projecting his own regrets over his failure to kill Sozin onto a radically different situation, driving Aang to cut ties with him for a year. When they reconcile in The Rift, Roku acknowledges his own failures and states that he and his predecessors can only give advice from their own perspectives; Aang must balance the past and present, much as he must be the balance between humanity and the spirit world.
Korra deconstructs Child Prodigy, Goo Goo Godlike, and Stock Shōnen Hero; For the former two tropes, as stated above, most Avatars discover their status when theyre sixteen years old when the spiritual leaders of whatever nation they belong to tell them. In Korra's backstory, she discovers she's the Avatar for herself when she's four years old because she was able to not only bend her native element of water, but fire and earth without any proper training. She never got a chance to grow up emotionally due to spending her whole life pre-series inside a compound training to be a hero and responded poorly when first faced with genuine adversity. It also caused the lack of a self separate from being the Avatar because for as long as Korra could remember, she has always been destined to be the Avatar. This ends up resulting in Korra tying her self-worth to the occupation, so she always goes through an identity crisis whenever that status is threatened. A major part of her Character Development is learning how to love and accept herself beyond her identity and expectations of the Avatar. For the latter, her recklessness and Hot Bloodedness combined with her lack of social skills due to her sheltered upbringing is just as likely to alienate her allies and accelerate the plans of the villains as it is to save the day. Another major part of her Character Development is learning how to be more mellow and actually think things through.
Asami Sato deconstructs the Mad Scientist's Beautiful Daughter and Romantic Runner-Up. In the former's case, being vehemently and actively against her father still makes her guilty by association whether it's being arrested by Tarrlok for being his daughter or Future Industries having a tainted reputation from her father's actions, requiring years of effort to restore it's good name and reputation all by herself. In the latter's case, being repeatedly ignored and disrespected by her boyfriend adds salt to the wound of the former to the extent of a rebound out of loneliness and desperation that's both embarrassing and leaves her jilted again. It's only by time and effort, ironically with her former romantic rival, that she catches a break.
Bolin deconstructs the usual comic relief Idiot Hero. Contrary to Mako, being shielded from a Crapsack World not only leaves him feeling insecure in the presence of his brother, but also immature and Super Gullible that makes him a sucker for any sweet-talking villain. This eventually stops being cute and gets him brutally reprimanded when he joins Kuvira, the Arc Villain of Book 4, because he honestly believes she's trying to restore the Earth Kingdom even when evidence of her dictatorial intentions start to show, leading him to actively work to redeem himself and finally grow up.
Mako deconstructs the usual Pretty Boy lead, especially in a Wish Fulfillment-loaded Betty and VeronicaLove Triangle. In Book 1, he's introduced as both handsome and competent in deftly taking down an entire team by himself and spends most of the season being fawned over by two attractive yet contrasting women and ultimately ends up with the heroine with whom he's had a purely Belligerent Sexual Tension-type dynamic. It's not until Book 2 when the deconstruction hits that he and Korra don't really work well together, and that same dynamic leads to him breaking up with Korra, rebounding to Asami then back with Korra under confused circumstances; this ultimately ends with him single, embarrassed, and looking like a jerk to most of the cast.
Baatar Jr. deconstructs Generation Xerox. He debuted in "The Metal Clan" just like the rest of his immediate family (and fiancé,) but whereas his siblings have Meaningful Names and Establishing Character Moments not only is he introduced simply as a Satellite Character to his father, only referred to as "my oldest" by Su-Yin, but he doesn't even talk as he's AWOL to the fight between Lin and Su in "Old Wounds" despite everyone else in the family being there and generally seems the absolute least like Toph overall. Turns out, he's had a chip on his shoulder all along exactly because he's seen as a mere clone of his father, to the point where he hates being called Junior, and part of the reason why he joined and eventually got engaged to Kuvira is because she allows him be his own man. He's practically a background extra raging against the author for being so unremarkable.