(Click on the names of the teams for the importable!)
A balance team which was built around CM Groundceus. Both it and M-ray wreck havoc while the rest 4 mons provide solid support. Defensive Yveltal takes care of many setup mons with the help of foul play. Taunt helps significantly with Ferrothorn, which is a pain for the team. Necrozma can be used to absorb Toxics thrown at Groundceus and baiting a Will-O-Wisp onto Groundceus if possible is beneficial (preferably by using Necrozma/Ray-M). Avoid Toxic on Groundceus at all costs unless it is guaranteed to sweep the opponent's remaining mons without getting stalled/phased. Double rocks are there to pressure Ho-Oh better, which is the best CM Groundceus check in the tier. Stone Edge is there on Primal-Groudon to OHKO Ho-Oh if it decides to stay in and defog, avoiding the Defog simultaneously. Avoid Toxic on Yveltal if possible.
This team was built around CM SteelCeus & Ray-M, as both of them take care of each others' checks really well except Marshadow, which is why the team has 3 Marsh switchins (FairyCeus, Zygarde, Ho-Oh). SteelCeus is notable for not fearing Toxic unlike Groundceus but it gets walled by Ho-Oh even harder, so the team has double rocks. Ho-oh is the main Geomancy Xerneas check, with Groudon-Primal being a backup check. Waterfall is run on Ray-M to OHKO Primal-Groudon while also heavily damaging Tyranitar, and V-Create for the ever-annoying Ferrothorn. However, Ferro isn't that much of a problem for Steelceus as the latter is immune to Toxic; in fact, Ferrothorn can be used as setup bait for Steelceus. Any one of them can be replaced by Outrage if the user wishes to, however. Dragon Tail on Groudon-Primal can be changed by Stone Edge for Ho-Oh.