the reason nobody talks about these mons is because they suck. Neither of them is bulky enough or has reliable-enough recovery to do anything useful. While it's a cool concept to trap things and go out to a setup sweeper, the reality is that since you expended your dyna in order to get the trapping effect in place, you're going to seriously struggle to get much mileage out of your sweeper since your opponent has defensive dyna available to them. For instance, if you expend your dyna to trap, say, a defensive NDM, then switch out to, say, a swords dance Groudon, the opponent can just dyna their NDM and win the 1v1. Also, having to commit a whole team slot to these trapping gimmicks can severely hamstring your ability to have any sort of useful offensive presence, given that three slots are already taken up by the obligatory defensive core.
One thing I’m surprised about is the lack of discussion on Sandaconda and Centiskorch, particularly their G-Max moves. These 2 have G-Max moves that are essentially upgraded versions of Sand Tomb and Fire Spin respectfully.
However, what many people don’t know is that those effects remain even if the user switches out. Basically, Sandaconda/Centiskorch can Dynamax, use their respective G-max move, hopefully hit something passive and without ways to escape, and then switch out to a set up sweeper.
With Grip Claw, you can have 6 whole turns being able to do what ever you want while what ever was trapped takes 7/8th of damage from being trapped.
tl;dr: having to use your dyna for this sucks since it limits your sweeping options