Ok
ワリオの相棒。ルイージをライバルだと思っている、変わりもの。キザでずるがしこく、ひねくれた性格。マリオやルイージとたたかう力をたくわえるために、かくれたところでがんばってきたらしい。けっこう、努力家なのかも・・・!?手足が長いので、それをいかしたスポーツで活躍することもあるよ。でも、いつも姿勢がわるいから、あんまりつよそうには見えない・・・。ちなみに、ワリオとはよくいっしょにいるけど、兄弟ではないらしいよ。
"ワリオの相棒"says "Partner of Wario". The word in this sentence can also be used as "accomplice" or "companion". "ルイージをライバルだと思っている、変わりもの。" says "I am thinking that Luigi is his rival, an eccentric". Now this, "キザでずるがしこく、ひねくれた性格。マリオやルイージとたたかう力をたくわえるために、かくれたところでがんばってきたらしい。けっこう、努力家なのかも・・・!?" translates to "Cunning affectation [that part was harder to translate for me, it also correlates to the English words "niminy-piminiy" and "foppish" to be exact, basically a conceited, over-dramatic, affeminate fellow; but "affectation" summed up all those words for me and made more sense with the sentence], twisted [or perverse; refers to abnormality, hostileness, and cynicism] personality. In order to store the power to fight against Mario and Luigi, it seems like he does his best at a hidden place[?]. Fairly difficult, perhaps a hard worker...?!"
"手足が長いので、それをいかしたスポーツで活躍することもあるよ。でも、いつも姿勢がわるいから、あんまりつよそうには見えない・・・。" is "Since he has long limbs, he shows great activity in sports. But, because his attitude is bad, it does not appear he has any strength"
Finally, "ちなみに、ワリオとはよくいっしょにいるけど、兄弟ではないらしいよ。" translates to "By the way, it seems Wario is not a brother but there is well being together [?]" (or it might translate to the narrator taking a break and pausing in between that sentence, but it's hard to translate)
Basically I translated this
"Partner of Wario. I am thinking that Luigi is his rival, an eccentric. Cunning affectation, twisted personality. In order to store up the power to fight against Mario and Luigi, it seems like he does his best at a hidden place. Fairly difficult, perhaps a hard worker...?!
Since he has long limbs, he shows great activity in sports. But, because his attitude is bad, it does not appear he has any strength"
This is a rough translation, like I said, and I have limited proficiency in Japanese and how it works we have to wait until an well-knowledgeable translator comes along. But I hope this helps. :P
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I went ahead and translated Wario's bio. Pretty interesting too.
His childhood friend is his biggest rival (Mario), "or so that's what he says." He's strong and he has a personality that doesn't worry too much about little things. He would do anything to earn his money, and so he's an adventurer, traveled the world to find treasure, and is a president of his own company. And his favorite food is garlic which he eats every day. It also greatly helps his stamina.
(why are wario and waluigi friends again, total opposites)