Heatran duo without Groudon&rejoin?

If pokebattler sims are correct, no rejoin duo is extremely difficult to pull off and doesn't actually involve Groudon for most movesets. Assuming BF bonus:

Iron Head: You need both players to have 6 maxed Kyogres. Against Fire Spin you also need good luck.
Fire Blast: Both players need either 6 maxed Rhyperior (Fire Spin) or a mix of maxed Rhyperior and Rhydon (Bug Bite).
Stone Edge: Both players having 6 maxed Rhydon can pull it off with luck. Any Rhyperiors or Groudons help, probably 1 each is enough to make it fairly consistent.

I can duo it in cloudy and rainy weather (all Heathran moveset), with no groudon and not all maxed counter
I cant do it without rejoining though, but i use 2 battle parties
I start with Rhydon, 1 at max, others at lv 30-35ish (basically my old squad againts old Raikou raid boss)
Folowed by full squad of Machamp at lv 35-40 in cloudy, and 1 kyogre, 4 gyarados, 1 vaporeon in rainy weather. Gyarados and Vaporeon is my old gym defender, so pretty much max or almost max out.
I dodge a bit when i am using my Ground squad, so my 2nd battle party can survive longer with no dodging, avoiding a 2nd rejoined ( happens at my first Heathran raid)

Other acc using full Machamp lv 35-40, followed by 1 Rhyperior and Golem at lv 30ish, and Kyogre, 2 Gyarados and 1 Vaporeon at lv 35ish in 8000 stardust
No Sunny yet, but get a time's out at Partly Cloudy (Iron Head). I replace my 2 lowest Rhydon with Groudon at Lv 30 to win it, so i am using Groudon now altough i think still can do it without if i evolve my Rhydons to Rhyperiors but i save my candy and TM.
All win with a so so TTW between 10-20ish second. But that is enough for me, a win is a win. I dont wanna burn more resources just to get a better time.
When i get times out again vs another moveset or weather, i am gonna power up or change my squad a bit, just enough to win it