What should I do with these Tyranitars?
#1: L30, SD/Cr, 15/10/15
#2: L30, Bi/Cr, 13/15/13 (first and, for months, only)
#3: L26, SD/Cr, 14/15/11 (CTMed from FB)
#4: L25, SD/SE, 14/14/14 (raided during CD, CTMed from FB)
#5: L20, SD/SE, 12/15/15 (saved, CTMed from Cr)
#6: L20, Bi/Cr, 12/15/15 (raided before CD, CTMed from SE)
#7: L17, SD/Cr, 12/15/14
#8: L6, SD/Cr, 15/14/13 or 15/13/14
CTM count dropped from 11 to 4 immediately after CD (now 6 thanks to legendary raids). Currently have 19 FTMs with no other good candidates (perhaps until I evolve my 96% Chansey, 98% Magikarp or 87% Feebas, all earned during Water Festival).
Think two Dark Tyranitars and two Rock Tyranitars should be enough for now. Alternatives are a level 30 Houndoom and two level 30 Golems.
Should I feed #1 a FTM or just power up #6 to get my second Dark? As for the two Rocks, is #8 worth more CTMs and dust, compared to #5 and #6 which already have SD/SE?
Answers
I'd keep them benched for later, dark is more prominent in raids at the moment (if alakazam and gengar return) and mewtwo's EX raid, rock's only use will be when rayquaza and regice are added (the birds and beasts likely wont be back for a long time as they'll be research rewards)
Long story short, keep the smackdown ones, any non smackdown ones should be converted to double dark unless steel weak pokemon are prominent in your areas gyms or what you want to be raiding, if there is a ground event, raids will likely shift to rock/ground types and piloswine will also likely be back
For trades they could be good bargaining chips for things like shadow claw gengar or other high value legacy move pokemon/legendaries
Keep the Smack Down, no need to power it up or TM right now, just wait till it become usefull in Raid..
If you dont have the need for Dark Tyra right now, just wait also. Tyranitar is still a T4 raid boss
If you need it for Mewtwo raids, you need more than 2 if you want to trio it. 6 is preferable for anti Mewtwo without Focusblast, can use it as a backup squad against Focusblast though, if your main Focusblast Mewtwo counter squad is good.
If you are doing Mewtwo raid with manny people, what you have right now is OK..