the anime we got was always quite plain on it and since the end of the Johto saga i dropped it for good reasons (we talk about several years ago).
what have i noticed that we use "Cry" similar of those of the anime serie , AKA: pokemon screaming their names.
since the first games to Arceus fight, when clicking to any pokemon we would NEVER read them using their name as a cry instead something that would sound more like an animal ( you can research that or even get you old Red/Gold/Silver/Platinum version and check every pokemon sprite if you want, i've already done that and can even prove it if requested).
i know that for copyright issues using their original games sound would be not convenient, and in a minecrafty sandbox-like exploration hearing their "8bitish" cries would be even worse, so i had a better suggestion.
if we take the new specials as example: Pokemon generations (i doubt there is something more lorefriendly and more like the games than these specials)
we can clearly hear that EVERY pokemon there sound exactly like animals, not even Pikachu says its typical "Pika-Pika" instead sounding like a Mice.
so i just suggest to find the cry-noises of the animal that represent its pokemon counterpart (or in case mix some animals noises like they did for the Jurassic park series to find the sound that most goes along with our Giratina) , edit and use that as its cry (making harder to recognize that pokemon noises that you hear outdoor for example)
Source:
https://www.youtube.com/watch?v=ktskEn5q7gg
or any other of these specials
give me your impression