In the situation with 2 garchomps, if ripple swell doesn't seem to be an option, playing in that fashion isn't smart gameplay.
Play each energy on a benched 90 go arceus and dare them to take one out or take out the active. If they ko the active, move another up, move energy up, lvx, ko. Then you have 120HP undamaged omni that may/should be ready to attack next turn (depending on type advantage/flip for bright flame, if needed.). Continue to spread energy in safe locations and retreat/switch/warp energy as needed.
As obsidius stated, there are variants that are focused on ripple swell, so in may be possible that those decks would suffer much harder w/o ripple swell, they probably suffer pretty hard under trainer lock as well.
Its not as easy to play out of a non ripple swell, but entirely possible. Its good that people think that way, it can be a shock when arceus is set up for ripple swell and you bypass it to begin a well formulated attack.