Bite/Stone Edge Ttars
Is there any point to keeping one, if you have enough Double Rock Ttars?
Is there any hypothetical matchup where Bite/SE would be useful?
Answers
Bite stonedge, no, but bite crunch yes, its going to be the most useful tyranitar set until rock weak raids happen (the earliest possible ones will be Rotom's alternate forms, which may or may not be added, but definitely when Gen V's legendaries drop, and that wont be for a good while)
I'd recommend stocking up on charge TM's to make them bite crunch, I have 6 double rock tyranitar, and thats what im converting all my old ones into
Considering that several legendaries have already been rereleased with shiny forms available, the gen 1 birds have a decent chance of reappearing in raids. If they do, SD Tyranitar is going to be MVP.
Also why Rotom in particular? There are plenty of other mons that have been or could be raid bosses that SD Tyra would be good against, like Jynx, Charizard and Scyther.
I had a 98% L39.5 Tyra with Bite/SE which I CTM'd to Bite/Crunch.
I just don't see a reason where you'd be better off utilizing Bi/SE ahead of SD/SE, or Bi/Cr; Scyther and Jynx have been mentioned, but SD/SE outperforms alternatives against the former, and Crunch is a better option against the latter.