I really doubt Terrak and Pinsir will end up staying in UU if it drops. Terrak has a great speed tier (Scarf would be the fastest in UU), has the perfect STAB combinations, with two boosting moves. I think it could be managble, to stop fat things like Suicine and SubCoil Zygarde from setting up (fuck those 2 win con..), but I think it would make offense so much stronger than it already is. Tell me what's coming in on a banded CC lol
Pinsir has really good stats overall, only hindered by its typing, but honestly, that makes it even better since it gets STAB Aerilate Frustration, priority, and boosting moves.
Mega-Manetric I think would be perfect in the tier. Even with intimidate, it isn't able to take hits that well, and it also lacks the raw power to destroy the entire tier. Its movepool is rather static, with the only variations being HP Grass vs HP ice. I think it would be healthy!