In original Sun/Moon, I have this battle video: A28W-WWWW-WWW7-7AX7

It makes use of the move Ice Ball, which under this system can receive a 32x multiplier on its own: 2x for each consecutive use up to 5 turns, and another 2x if it was preceded by Defense Curl in the first place. Being maximally rosy, we have:

32x for Ice Ball "turn 6"

8x for type

2x for Pure Power

2x for full strength Metronome

4x for Attack +6

4x for opponent Defense -6, though it would be trivial to manipulate this up to being worth 7x by using a level 5 Smeargle instead of level 1 as the damage recipient

3.375x for triple Helping Hand

1.5x for STAB

1.5x for critical hit

1.5x for Flower Gift

All together, that's a "multiplier" of 186624 as-is, or 326592 if you use the stat manipulation to get 7x from a -6 defense drop. In fact, you can think of Power Trick as giving about a 5x multiplier to the attack stat in the first place, given the way the stats were actually aligned in that match, or if you want to be even more extreme you can manipulate the stats so that Power Trick represents an increase of about 28x--if you count that, you could be looking at a "multiplier" of over **9 million**. Hopefully this demonstrates the frivolity/uselessness of looking at multipliers alone, whatever's supposed to count under that umbrella.