Late but here I am.
This match is similar to their preliminary match where they're massively outclassed in AP/Dura (tho they won't get one-shot anytime soon due to not being 8x gap) and outranged, but that's where the similarities end, since this is way easier than the previous match.
Now that this battle takes place in trenches, the riders have ample room to take cover as they make their way to the mercs. It's an added plus for them, despite already having the means to deal with the danmaku via Shadow Moon's Telekinesis. Thankfully, the danmaku is just a straight line and not anything else so they won't have as much difficulty as the deltarune duo.
We do have to get two elephants out of the room first, AKA the violent tendencies of the rider duo and the merc's ubercharge that grants invulnerability.
Unlike last time, they're straight up facing humans this time, at which they won't usually go for the kill. Shadow Moon is a bit more bloodthirsty than Black Sun in terms of dealing with humans due to some story stuff that happened, so if he woke up on the wrong side of the bed that day, he's going to pile up some kills. While Black Sun himself usually doesn't go for killing humans, he is neutral to his best friend doing such things.
The mercs would start off popping their canteens to ubercharge, which would last 5 seconds since their main ubercharge would take a while. I assume that they will only be immune to damage, so Shadow Moon's initiating TK will knock them down or raise and turn them away from the riders at the very least so that he can use TK to pin them before their time is up and then incap/crush them. Medic's resurrection would mean squat if he just keeps getting crushed if he gets killed, Nobuhiko just needs to exert more effort in killing him more, assuming he goes for the kill. In the case of incap, non-lethal TK.
Due to their enhanced senses, the rider bros will be on the initiative first and can probably catch the mercs off guard too with the infamous TK, knocking off all their weapons and canteens from their hands along with pinning them down too. The riders' Class M LS is going to be a ***** for the poor mercs' Class 5 LS.
This match does lean towards the riders more (much so than the equally matched Deltarune one).