HONG KONG, May 25 (Reuters Breakingviews) - China’s Great Wall Motor (601633.SS) has made a rare public allegation that BYD’s (002594.SZ), (1211.HK) Qin Plus and Song Plus hybrid models do not meet emissions standards in the country. Thursday’s accusations sent BYD’s Hong Kong-listed shares down 5.4%, but the whistleblower’s own stock fell 7.3% by market close. There’s a lot at stake for BYD. Its hybrid deliveries have doubled to reach nearly 400,000 in the first four months of this year, accounting for more than half total sales and helping it to quintuple net profit in the quarter ending March. But...