some more...
Gengar: in Japanese has to do with something you say after you play a prank on someone or Dopplegengar, a ghost that lurks in the shadows and copies people
Lapras:derived from its Japanese name "Laplace" named after a scientist who studied the waves
Pikachu: pikapika (Japanese onomotopoeia for "Light Sparks.") + chuchu (Japanese for sound a mouse makes.)