Someones said TRANSLATIONS? My Japanese may be a little rusty but here you go, I found a Website named Ultimate Pokemon Center and let's get into the business.

CUBONE
Red/Green:
Shiniwakareta hahaoya no hone wo atama ni kabutte iru. Sabishii toki oogoede naku to iu.
しにわかれた　ははおやの　ほねを　あたまに　かぶっている。さびしいとき　おおごえで　なく という。
Wears a bone of its dead mother in its head. Is said to raise its voice crying when lonely.

Blue:
Atama ni hone no herumetto wo kabutte iru no de hontou no kao wo mita mono wa inai.
あたまに　ほねの　ヘルメットを　かぶって　いるので　ほんとうの　かおを　みたものは　いな い。
Since it wears a bone helmet in its head, nobdy has seen the true face.

Yellow:
Nakigoe ga nigiyaka na no wa mittsu aru atama ga sorezore suki na koto wo kangaete iru kara da.
なきごえがにぎやかなのは　3つある　あたまがそれぞれ　すきなことを　かんがえているからだ 。
Its head has three lively cries because they are all considered good.

I clearly couldn't translate the Yellow entry correctly, but it seems that, according to the Japanese originals, too, every Cubone's mother is dead. I might do more later.