Power Up Punch would be devastating for Brawly, considering at lower levels OHKOs are not so common and every Pokémon has decent bulk. By the time his Machop finishes with Combusken, he would be able to OHKO Taillow before Taillow can land in the second Wing Attack.
I totally agree about the Trick Room part, especially since it's a double battle and most of their Pokémon spam Calm Mind, but their original TM Calm Mind was probably the most useful TM in the entire game (basically OHKOd Wallace's entire Champion team), so I'm hoping we get that instead.
Flannery could use Overheat and Flame Charge to her advantage because of the Physical/Special split, because using Overheat wouldn't affect Flame Charge's power if you manage to scrape by with low HP. Wattson should definitely give out Charge Beam because his Manectric and Magneton would be much more deadly if they are equipped with it, a few Charge Beams and Double Teams and then Thunderbolt.