>>54293663Tyranitar is still very strong, still sees solid use in natdex, BSS, and saw use in Reg B and C VGC. It being RU in SV OU is just one metagame, and not indicative of the Pokemon as a whole (and likely temporary in the grand scheme of things).
Octillery has always been a total shitmon, it's never had a viable role in any meaningful way, much less the higher tiers.
Houndoom was a UU staple for much of its early life and usable in OU, not bad. The Mega also was solid.
Jumpluff has had use in VGC.
Umbreon, Blissey, Hitmontop, Forretress are all decent at worst today.
Politoed is totally outclassed by Pelipper (unless that Scald situation pans out favorably for it), and Xatu by Hatterrene. Still technically got way better, but their performance doesnt show for it in the same way Slowking does, for example.