Just a list for no reason whatsoever. Interpret as you will.
According to lore, long before the Toa Mata lost their memory and Takua had his wiped a thousand times, Takua was most drawn to Toa Gali and was awestruck by her.
Despite being hidden as a Ta-Matoran, Takua wore an ill-fitting medium-blue Pakari. No other Matoran or Toa of Fire in the entire series have blue as a part of their color scheme.
Takua never really fit in in Ta-Matoran society and was never able to fully conform to Ta-Matoran mannerisms or values. He was considered bizarre in Ta-Metru, and became an outcast in Ta-Koro.
When cast out of Ta-Koro, Takua finally found community for himself among the other members of the island who were considered abnormal or pariahs.
During the time after the Toa Mata arrived on Mata Nui, the Toa that Takua bonded with the most, and even forged a psychic link with, was Gali.
After the Bohrok invasion, when the Matoran were rebuilt into larger, stronger forms, Takua chose to replace his yellow with blue for reasons never stated, making his color scheme now mostly variations of blue with only a red torso and arms.
Takua having multiple blues in his color scheme isn't just abnormal because it's not an established Fire color, but rather because almost every kind of Matoran with heavy amounts of blue in their color scheme is exclusively female (Water, Lightning, Psionics).
Takua spends the majority of the Mask of Light movie chasing an ideal person whom he is convinced must be someone else, and when faced with repeated signs of who he truly is, ignores and hides from them until it's almost too late and his loved ones are pushed away and hurt by his avoidance.
Unlike all other Toa transformations seen in the series, Takua is only ever able to take action to physically change into who he was meant to be once he finally accepts who he is and who he is meant to become.
Also unlike all other Toa in the series, Takanuva is the only Toa to change their name upon self-actualizing into a Toa. Matoran change their names slightly at times throughout their lives, but Takanuva's name change is the only one known to directly tied to a change in body, presentation, and social identity.
Upon confronting the main antagonist of the series, Makuta Teridax, the Makuta immediately demeans and belittles the newly transformed and renamed Takanuva by reducing him to his past identity as Takua.
The canonical explanation for the form a Matoran will take upon becoming a Toa is that they will take on the form of what they consider an ideal hero. For the Toa Metru, that was Toa Lhikan. Takanuva is stated to have taken on the form of a Toa Nuva, but every member of the team had somewhat unique builds; Takanuva's build is the exact same as Gali Nuva's.
Later in the series, we learned Takua was never even a Ta-Matoran to begin with, but actually an Av-Matoran, and was simply made to think he was something he never was while constantly failing to perform that role.
Takua was meant to be an audience surrogate character for MNOG, QftT, the Bohrok animations, and Mask of Light, and did a fantastic job at that.
Unrelated, but a disproportionately large chunk of that audience has since grown up and transitioned into women, many of whom idolize or once idolized Gali. Funny, that.
Takanuva literally sparkles when they walk and wields not only deadly lasers but the literal power of friendship and empathy idk what else to say about that lmao. Do I have to spell it out?