Actually, ライトニング is just the English word as written by the Japanese in katakana, their alphabet for foreign words. Lightning is actually かみなり (kaminari) or でんこう (denkō), while a flash of lighting can be いなびかり (inabikari) or いなずま (inazuma), and lightning bolt is らくらい (rakurai). All of these also have kanji, which are as follow: 雷、電光、稲光、稲妻 and 落雷. There are also several others that I can't be bothered writing out.
そですか私は知りませんでした. You got me you got me. I am learning Japanese and when I would play Pokemon in Japanese the Heart gold version they used lightning in that context.
You can check out an app called Human Japanese it's really great. You gotta pay for it but there is a trial version. So test it out and if you like it get it. It's like 70% of my source for learning so far. Also there is an app called Hello Talk. You can use it to do language exchange with Japanese people. They teach you Japanese and you teach them english or whatever you are exchanging. Those our some of the tools I use so I hope this helps you
Pika is a Japanese onomatopoeia for the sound sparks make, chu is a Japanese onomatopoeia for the sound a mouse makes.
Also this is just conjecture, but the "rai" in Raichu is probably just the first syllable in "lighting".
Also this is just conjecture, but the "rai" in Raichu is probably just the first syllable in "lighting".