As for my opinion on Regice, since it's written as レジアイス (Re-ji-ice) in Japan, I just go with that.
Pidgeot, to me, is Pid-jot, though the Japanese is "Pidgotto" (Pidgeotto in Japan is "Pidgeon")
Tropius is as in "tropism" rather than "tropical". I should've guessed.
Bonsly, as in Bonsai trees. Makes sense since it looks like one.
Tangela: Tang-ellah, used to pronouce it as Tang-ah-lah... XD
Blaziken: Blay-zike-n, used to say Blay-zik-en
Zigzagoon: Zig-za-goon, used to say Zig-zag-oon.
Linoone: Line-noon, used to say Lin-oon.
Gardevoir: Gar-deh-vrah. Kinda hard to make it pronounce it right online xD
Aron: A-ron... Always found this too awkward to pronounce.. T_T
Milotic: Mill-o(as in otter)-tick
Tropius: Trop-ee-us(not as in us, like... Idk xD)
Bonsly: Bon(as in on)-sly
Uxie: You-xee, awkward huh? XD
Dialga: Dee-al-gah... T_T yes I pronounce it that way!
Arceus: Ar-soo. Idk why I pronounce it that way. My brother makes fun of me for that. :/
That means I don't pronounce an sound, but instead a long [e], like deus in latin. Furthemore I give emphasis to the second syllable, so it sounds more like "Arc Deus".
I would give a list with all pokemon names but...
I pronounce Pidgeotto the way Italians would prounce it instead of Pidge-EE-oto. I pronounce Ho-oh How-how, as my friend told me it was pronounced like that about 10 years ago and I only recently found out it isn't. And I pronounce Arceus Ark-ey-oos. Don't know if that's the correct pronounciation.