Some of mine weren't too bad, and some were horrible.
I still don't know how to pronounce Regigigas. But anyway.
Onix= Oinks. I bought that Pokemon manual thing will I was little and I was a late viewer. I can't explain.
Togepi= TogEpi. Not bad. Just put the long E sound on it.
Hippopotas= I just totally butchered. I don't even know what I called it.
Hippowdon- Hippo-don. Not bad. Just forgot the W.
Happiny- Happen E. Vs Hap-pee-nee
Darmanitan= Darmation (like Dalmation)
Garbodor- Gar-Bore-Door (Fail)
Hydreigon- Hydro-gon (Fail)
What are some of yours? I probably have a lot more but I don't remember