I have a lot of Machamp plus 15 or so usable Heracross. Sure I've only fought Regice four times, but I've seen auto select pick the Heras. Maybe it was cloudy weather and Heracross has a better resistance to fighting and ground (other situations it resists grass better than Machamp). I obviously didn't use those Heras bc CC sucks.
That's the Sunnyside, anything else you can think of will favor Machamp. (I'm talking about Heras that are 2480 to 2580, if lower or near 2000...well, do a boosted Machamp raid til you get DP)