>>58700721Serena is consistently taller than Ash, and May is consistently shorter than Ash. They're both clearly stacked in their own rights, but their height difference means they fill out differently.
Also, if we accept that both are busty and both have lots of junk in their trunks, Ash would be a very lucky boy if his two good friends, who themselves have become good friends, both decided they wanted a threesome. 