Ooh, if we're writing fanfic scenarios for this battle, then I've got one with Pikachu sort-of-realistically jobbing.
Sirfetch'd vs Hawlucha: Sirfetch'd wins mid-high diff
Lucario vs Grapploct: Lucario wins mid-diff, low diff if it goes Mega right away
Machamp vs Pikachu: Machamp G-maxes and takes out Pikachu, but get paralyzed from Static
Machamp vs Lucario: M-Lucario manages to make Machamp run out of Dynamax juice, but faints in the process
Sirfetch'd vs Machamp: Sirfetch'd avenges Lucario and Pikachu, and wins the battle for Ash
There you go. Everyone gets to contribute against Machamp, G-Max is properly shown as a threat, Megas get their not-based-on-a-timer advantage, and the duck gets a pair of solid wins.