Hidden Details: Gym Rats

Welcome to the one-hundredth-and-eighty-first episode of the Hidden Details blog!

Have you found some obscure reference or detail in this comic? A JoJo reference? A sneaky little Loss? A callback to a previous comic? Let us know what you've found in the comments! Every detail that has been found will be added to the list below. Once everything has been found, this comic will officially be marked with "all details found".

Link to the comic for your convenience

Please only comment with ONE hidden detail or reference!

There's one Loss, one Balthazar, one Miep and one crewmate. Bonus comics don't count.

FIRST PANEL
1: Chris is indeed wearing a "Boulder" tanktop referencing his infamous boulder punch from Resident Evil 5, BenjaMan64.
2: Newt from Xenoblade Chronicles 2 is using her floating arms to lift a massive Barbell, much to Sol Badguy's shock.
3: There's a little Nopon on Newt's shirt in the first panel, as pointed out by KevDu.

SECOND PANEL
4: Ike is wearing tanktop with a parody on the Nike logo, simply saying "Ike". Found by Cameron Devera.
5: I love hiding loss in sweat, A Sad Fat Dragon with No Friends. Glad you noticed it!
6: While nearly everyone is wearing custom gym clothes, Samus is just wearing her orange alt from the actual game.
7: The sign that says you can't bench-press cars is a little foreshadowing to Undyne's appearance later in the comic, since she does bench press a car in Deltarune.

THIRD PANE
8: It does seem to be a coincidence that both Malenia and Let Me Solo Her are present in the same gym, Fighting Master. I agree, it's likely that they're training to beat each other.
9: Speaking of Malenia: there's a crewmate hidden in her scars, as pointed out by Daniel Myhre.

FOURTH PANEL
10: There's a little Squirtle face on the water cooler in the background. Guess it's Squirtle-branded, Brandon Digwood.

FIFTH PANEL
11: Doom Slayer leaves his helmet on during workouts, as mentioned by Williams Fan 92, although you thought it was Master Chief.
12: Balthazar is running on the treadmill in the background of this panel. Found by Pixelman86, who also mistook Doom Slayer for Master Chief.
13: There's a sign asking gym visitors to re-rack their weights. Everyone who has ever been in a gym will know these signs are very common.

EIGHTH PANEL
14: Miep is watching Toad being arrested in the final panel, as pointed out by Generic Hero.
15: Wario and Waluigi are being paid in Nook Tickets instead of actual money. I hope they don't mind.

All the details that have not been found are marked italic.