If I'm not mistaken, DNA=Deoxyribonucleic Acid. So Deoxys comes from some words in its beginning.
I'll add some more:
Sunflora : Sun+Flora
Sunkern : Sun+Kern
Bellossom : Blossom
Lileep : Lily+Deep (I think)
Claydol : Clay+Doll
Manectric : Mane+Electric
Duskull : Dusk+Skull
Dusclops : Dusk+Cyclops
Camerupt : Camel+Errupt
Sharpedo : Shark+Torpedo
Clamperl : Clamp+Pearl
That's all I can remember.