Tele-DAD back in the day was alright but Lightsworn were better IMO. Blackwings upon release were better than both too also. 2 Dark Strike Fighter. gg.
Hell nah Tele-DAD always wins lol. Tele-DAD was at least like 14/16 of the top, and I beat LS consistently in Matches. 2 DSF < JDs & DADs.Dracian, there's no use arguing small points like that. I was going to say the only time you would mix Mewtwo & Raikou (OU) is in 2nd Gen. meta, but that's irrelevant. I cut that part out since I didn't think it mattered (since it is outdated game lol).
Here's what you listed:
Breloom, Garchomp, Gastrodon, Infernape, Jellicent,
Jirachi, Keldeo, Landorus-T, Latias, Latios,
Metagross, Politoad, Scizor, Skarmory, Starmie, Tentacruel, Venusaur
I crossed out those who are guaranteed to get OHKO-2HKO'd upon switching in to a Choice Banded Close Combat, the most common set for Terrakion. The Psychic-types take at least 50% from Close Combat & are cleanly killed by Stone Edge, so it's not a good idea to have them come to take Terrakion's attack. However, most of them can be fast enough to revenge kill Terrakion. "Revenge kill" because something fell to Terrakion to allow a clean switch-in to face him. And that is why Terrakion is so good - he's at least a guaranteed 1-for-1.
Infernape & Keldeo tie in speed with Terrakion. They'll win if they are Choice Scarfed and Terrakion is not. Chances are if you see someone switch in a Pokemon that has equal/lower speed than yours, it's Choice Scarfed. From there either they attack & kill you, use U-Turn/Trick (if they have it) to mess up your switch-in, or switch again to counter your switch-in. These kinda crucial moments define a battle. You can never be too sure.