Tera is EXTREMELY problematic for the metagame in my opinion. I won't bother writing a lengthy post about why this is, you've probably seen a million already, I'm not scrolling through this whole thread. What I will do is go through each mon on the radar and see if they're worth being on there without Tera. I want to emphasize, everything here is just what I think would happen. Feel free to argue for or against anything here.
A lot of the strength of Annihilape comes from the fact it can Terastalize to beat its checks. Whether it be Water, Steel, or even Poison, it can easily beat whatever it needs to with that Tera slot. If you ban Tera, Annihilape becomes manageable by several strong special attackers, like Dragapult, Iron Valiant, and Gholdengo if they can come in on a slow turn or after a sack.
Personal verdict: Off the radar with Tera gone
Perhaps the most obvious abuser of offensive Tera. The most prominent example is Tera Flying Booster Energy Acrobatics, which absolutely rips apart most teams with the support of Crunch and Earthquake, along with other options like Outrage or Taunt to stop status or just blow the fuck up out of everything. If you ban Tera, the most broken set goes, but it is very possible that Roaring Moon could be very strong without Tera anyways. However, due to teams not having to worry about Acrobatics as much, they can focus more efforts into checking those other options.
Personal verdict: Might be off the radar with Tera gone
This thing CAN abuse Tera very effectively...but its still good without it. Really, really good. Honestly, I'm unsure of this thing to be on the radar even with Tera, but it is and I have to include it because of that. I think it makes sense to say that it's still gonna be radar worthy after a Tera ban if it's on the radar without one.
Personal verdict: Might be on the radar with Tera gone
Not a Tera abuser in the slightest.
Personal verdict: On the radar with Tera gone
Not a Tera abuser in the slightest.
Personal verdict: On the radar with Tera gone
I'll also go over some mons that I believe to be particularly problematic Tera abusers, although these aren't on the radar.
Clicks Overheat and wins. Specs and Scarf just dish out absolutely absurd damage calcs with Tera Fire. Its Specs Overheat without Tera does about 90% to specially defensive Clodsire, and it just outright OHKOs with it. I'm not confident in saying that this would be broken without Tera. Without that free Adaptability on top of Beads of Ruin, it becomes a lot easier to handle defensively, letting balance have a way better time.
It just doesn't fucking die. IDef BPress is a concept I always wanted to see explored in gen 8, and now I realize just how horrifying it is in gen 9. Garganacl with Tera Fairy can wall pretty much everything, and Salt Cure wears down its checks horribly fast, while not being worn down itself thanks to Purifying Salt blocking Toxic. Without Tera Fairy, it would have to suffer through that debilitating Rock typing. I think it's safe to say that Garganacl wouldn't even be mentioned in this post without Tera Fairy.
An underrated Tera abuser from what I've seen, this can rip whole teams open by just having the right coverage move. That coverage becomes significantly more scary when it gets STAB and the ability to take one hit. It isn't BULKY, but it can live Dragonite's Tera Normal Extreme Speed, so having those resists can really be a lifesaver. I've mainly been using Tera Electric, but Tera Ghost is also horrifying for cleanly OHKOing Gholdengo with Shadow Ball. Without Tera, it'd still be great, but it would not have those "Delete the opposing thing that should probably be checking me right now" buttons available as easily. It'd have to invest a turn in using Calm Mind or lock itself into one move with Specs.
It clicks the Extreme Speed button, and fucking everything dies. I've been running Choice Band personally, which has dizzyingly high damage for a priority move once you go Tera Normal. However, Dragon Dance is the most common set, usually in conjunction with Shed Tail Cyclizar. Dragonite is a weird one to evaluate, because it's using two broken elements(Tera and Shed Tail). However, it is an extremely good abuser of Tera, so I think it's worth including here. Without Tera, it would not have those extremely speedy STAB Extreme Speeds, making it easier to handle for most physical walls.