The starting tier is fine, if you take into consideration what weapons the gears use and what cog enemies you’ll be going up against and higher difficulties, they’ll be no worry of being op from tier 1 as I based it around gears 3s tier 1 in the roster with sire being the exception, I thought the sire would be fine because you actually have get past fortifications whilst getting shot at and then you have to actually grab someone to one-shot em, it’d be more effective to use the standard melee. As for the leech to function like the wild ticker except the leech is even weaker than a wild ticker I’d say! Primary focus for leeches is to weaken fortifications and enemies like they do in horde, the popper would act as the new ticker and the juvie the new wretch
The image above is the swarm tier list I made and below is the gears 3 list, if you compare the two I’ve only added one extra to the last tier and that was the swarm drone elite but he’d be expensive because he’s in the last tier, but consider the final enemies on waves 10 to 12 you’re are gonna need creatures like the swarm elite sniper and swarm drone elite else good luck taking down a sentinel or guardian.

As for the stump I feel its a perfect balance when you take into account cost and enemies too, dr1 destroyers with tri-shots would demolish a team of 5 players if they didn’t have something to even the odds, as for the RAAM and Jermad idea… as much as I love the locust and gears 3 beast, gears 5 needs it’s own take now so I feel swarm should be stealing the show for any kind of beast mode 2.0, cryo cannon for lizzie could be great actually then if she goes DBNO similar to Clayton with his mulcher she could pull out an enforcer like she used in campaign, the thing with the buzz kill scion is he’s purely a support character and you’d have to take higher difficulties into consideration as well as cost, yeah you might get a bunch of kills with the buzzkill on higher difficulties assuming you hit your shots but if you die that’s a lot of points spent on 1 creature per wave and you have to run over to the base again before time runs out too, I think the scion speaker will be fine, he’s already at massive disadvantage in horde because they gave him a cryo cannon and no ability to buff enemies, in beast mode 2.0 if you were buff enemies, similar to kantus in gears 3 you’d have to wait till the animation played out and run the risk of being killed before you finished healing your teammates.