>>56707935So based on official released and leaked concept art as well as the art for her figurine that you posted, she's around the 2nd/3rd bustiest main female character in the games.
Rosa is decisively the bustiest in the games based on that same kind of evidence.
May is sort of in 2nd because while ORAS seems to make her more slender, she eas originally a bit bigger, and the original RSE anime as well as the more recent Pokemon Evolutions episode with May and Zinnia (which uses her uodated ORAS design) has her pretty stacked, implying that's still the association the devs have for her.
Serena's in 3rd at the lowest - her official art all shows she's pretty busty despite being tallet and having a more slender figure than the other girls. If you want to interchange hee and May for 2nd/3rd that's fine.
What's interesting is that in the anime, when she returned in Journeys (which was a series whose designs generally removed girls' curves even more), she haf massive, extremely noticeable boobs compared to the other returning girls (like, she was the biggest the series had since AG May before they nerfed her for D/P). So Serena is definitely a strong contender.
There was an official bust size ranking up to XY for the girls in the manga commented on years ago but the author also said they probably can't say much there without getting in trouble. It waa also in the databook as their "slenderness" ranking, and he later tweeted about White (Hilda) because he forgot to include her.
There the order was:
Serena > Leaf > Kris > Rosa > May > Hilda > Selene > Dawn > Yellow (Manga character only)
