I've found that Gliscor without Roost is extremely exploitable by Pokemon like Woger (
who also easily handles Gliscor's Tera Water variant that's been rising in frequency), but if it takes out various Pokemon that plague it, it can definitely be a bit of a nuisance and the addition of Spikes was quite nice.
Personally, there are five Pokemon I have my eye on along with Shiftry and Mightyena (
one of my big analysis posts will be coming soon); I'll order them from top to bottom as most potential to very niche specific.
You'll be happy about this
mr.pink88 as Swords Dance Iron Fist Tera Electric Thunder Punch is insane and allows Infernape to reach some impressive feats like OHKOing multiple variants of Toxapex and OHKOing Alomomola with chip damage. STAB Drain Punch feasts on Gambit and other threats, while Infernape has access to Raging Fury (basically, Fire-type Outrage) to avoid the longevity problems of Flare Blitz if that's an issue for your teams. It's easily one of the best returning old mons and this is the best Infernape has been in OU in a very long time.
A fantastic physically defensive mon with a lot of coverage and utility options, along with superb defensive typing and two fantastic abilities (I run Levitate because the Ground immunity opens up so many more options for defensive counterplay - such as turning Great Tusk from checking Weezing-G to being checked by Weezing-G. Really underrated mon that has a strong niche if you can play around its flaws (very exploitable Speed and Special Defense).
Ribombee and Vikavolt are both niche but strong Pokemon in their own right that made Sticky Webs an actual viable playstyle again. Bug/Fairy is great coverage (and Ribombee's speed tier rules in the era of the Ogers), while Vikavolt's nuclear Special Attack, Levitate ability, and powerful slow Volt Switches are great utility for a team.
While I love Dusknoir, his niche is extremely specific to one type of set - max investment in SpD and HP allows it to 1v1 Calm Mind Ursaluna Blood Moon with careful play thanks to unique access to Haze, Pain Split, and Will-O-Wisp (
the attacking move is up to you, I usually just run Poltergeist to whomp Gholdengo but it has other offensive options).