Soniqua first appears in "Metroid", where it shows up and barfs on Sonic after Mother Brain says to "at least say goodbye to our kid before you leave". Soniqua later appears in "Tetris", where she is shown wearing Earthworm Jim's suit as a diaper. It throws away Earthworm Jim after he attempts to take his suit back by force. Soniqua appears again in "Mortal Kombat" to kill Goro before he kills Sonic. After running him over, Soniqua devours Goro (which shocks Sonic). It then appears in "Bomberman" when Sonic claims it's "Take Your Daughter to Work Day" but what he's really counting on is that Soniqua gets killed during the job so he wouldn't have to pay for child support. Soniqua eats the bombs that Sonic is supposed to defuse and lives (which is something he didn't count on) but she spits them out at Bomberman when she and Sonic are talking about going to some taco place and so Bomberman ends up dead. It appears once more in "The Battle: Part 02" to rip apart Mike Tyson and devours his flesh.
It's first apperance in season 3 is in Casino Zone Part 1, it gets recruited as demolition. In Part 2 however after EarthWorm Jim learns Sonic is captured, Jim tries to call it only to learn that she's in the van with him and Eggman where it accidentally coughs up bombs and causes the van to explode and it, Jim and Eggman get set on fire and they run around screaming. Part 3 reveales that it, along with Eggman and Earthworm Jim survived. It stays behind as her father and the others go to rob the vault. In the war saga, Soniqua appears on Family Feud with Sonic, Tails, Jim, and Eggman, in the end she gives out the right answer by telling a fart joke, and wins the game. In Wrestlemania, it's revealed that Soniqua can't get hung over no matter how much it drinks, as Sonic puts it, she managed to drink an entire bar the previous night. At the end of the episode it hits Amy with a chair. In Duck Hunt, Tails offers the Duck Hunt Dog, which had just mauled Sonic, to Soniqua who makes him it's pet, and in "It's on" it trains him to fight Pokemon.
In season 4, Soniqua and the dog first appear in Pokemon. Sonic and Thunderhead show up to win some money in a Pokemon tournament, only to find out they are battling Soniqua and the dog. Thunderhead uses his dragon hoping to win, but Soniqua has trained the dog so well it is unaffected by it and then he mauls Thunderhead. Pokemon Trainer wants Soniqua to kill Sonic because he doesn't have the money, but it kills Pokemon Trainer instead because it loves it's father. She asks sonic if they could take the dog home, but he says no. Soniqua reappears in "Scribblenauts" after Sonic wants it to try and type something down. Soniqua writes down "Avocado Tits" and a pair of avocado tits appear and Sonic pets it for doing a good job. It also makes a cameo in the season 4 finale "The Red Carpet".
In season 5, it appears in "Mother Brain" revealing to have also survived the theater explosion caused by Sonic. It quickly destroys Mother Brain's new lair, and accompanies it's Mother back to the Great Fox with Sonic and Tails. Soniqua largely spends the rest of the season following Sonic and company on space missions.
Despite the fact Sonic changes his future in season 6, Soniqua still exists. When Sonic is killed by Mario, it sets off on a mission to kill him to avenge her father by systematically killing Mario's goons. When it finally confronts Mario however, it falls for a trap that involves peanut butter and bread. Mario tries repeatedly to kill it, from dunking her in lava to constantly electrocuting her, only to discover she is impervious to most forms of injury. With his inability to kill it combined with her constant catchphrase, Mario's frustration hits a breaking point until a prank by Tails, Eggman and Earthworm Jim results in his mansion catching fire. Mario is shortly afterwards killed again by the Bullet-Bowser projectile, which had been meant for Soniqua.
Soniqua is the host of a game called "Ask Soniqua", featured on Volume 1.
Soniqua resembles a lump of mutated flesh, with blue tentacles for arms, Sonic-shaped spines on the back of her head, and two tires for legs. It wears Earthworm Jim's supersuit as a diaper, despite the fact Jim reclaimed his suit a long time ago. Soniqua is usually sweet, loving and innocent around those whom it knows. She is however also ignorant of the events around her, even to the fact her father tried to kill her before. It loves Sonic very much and is willing to protect him no mattter what. Soniqua's behavior suggests it is mentally impaired, though it is known to randomly show mental clarity, especially during her rampage following it's father's death.
Nobody is 100% positive about Soniqua's gender, if it even has one. Sonic had also called it a he in the season 2 promo. Hints of it being a girl were in "Bomberman" "Mortal Kombat" when it wanted "man flesh" and when Dr. Eggman called it a she. Despite this, Soniqua is generally considered by all to be female.
Soniqua loves Ice cream and man flesh.
At first, Sonic hated having to pay child support and wanted to kill it off but eventually, he sees value in it as shown in "Double Dragon" and the way it saves him from Goro along with Mike Tyson. He even admits he felt (kind of) bad for trying to kill it and values her a bit more.
Soniqua will often yell "Avocado!" for no reason at all. This has since become her catchphrase.
Soniqua possesses insane strength and is prone to fits of insanity, leaving fear of it' ultimately justified. Multiple times throughout the series it has brutally mauled characters to death such as Goro, Mike Tyson (twice) and Lucas. it's signature attack seems to be picking up it's enemies above it's head and ripping them in half.