They say they can manipulate the price of a certain cryptocurrency coin.
Yes they can manipulate the price of a certain coin by just buying a huge amount of it. Law of supply and demand. Whales are rich people so they can do what they want in a coin.
So how do they do that
As I said in my first answer, they will choose a specific coin to buy then they buy in huge amounts making the price to spike then they will set a price and when that price has reached already, they will dump it into your face.
who/what are the most famous and richest whales in the cryptoccurency world?
Nobody can say any people who belong in this so-called "WHALES" because nobody knows them in specific. We only know them in general terms. Maybe they are bank owners, they are rich investors. One thing is for sure for me, they are rich people holding billions of $$ of money.