Not sure as i haven't played it recently, if there isn't, it may not happen unless LaZ decides to, and no one knows, including LaZ as hacks are not like budget based games. there is no time frame set, and most hackers despise such questions.
Though IIRC on a really old beta, i did get a coupple of rematch calls on my pokegear, though i could simply be confusing it with HGSS or even GSC