The technically correct answer to this is as simple as “ポケモン”
However, I know that’s not what you mean.
Throughout anime and fandom history, there’s been so many different pronunciations that even the incorrect ones are correct. However, since the franchise originated in Japan, under the title of ポケットモンスター, also known as, ポケモン, I will teach you how to pronounce it that way, since it’s the most correct.
ポケモン reads as, literally, Pokemon. And thankfully Japanese is fairly easy to pronounce
The format is:
The syllable = me attempting to write out the sound (example of sound in American English)
Po = Poe, po, (as in Poke, to poke someone)
Ke = Kay, kei, ke (as in okay)
Mon = mon, mawn (as in Monster)
Tl;dr pronounce it however you want; there’s so many pronunciations to the point they aren’t wrong, but the Japanese way is the most-correct way, which is the way I attempted to explain above
Source: funny understanding of Japanese
I hope this helped