I think having some toons at G8 in ur team Zader will add u nothing... Because batles dont last enough time to stack dots (they will kill u before xD), and TM removal isnt that effective cuz once u kill some rebel pilots will get 100% TM anyway to use strafe and kill some of ur G8 toons... So adding a Z on vader wont make u complete 4/4 where u are getting 3/4...
Zidious is not a great toon here... He could be useful paired woth nihilus cuz hes so fast and can spread dots to make nihilus increase enemy CDs and prevent strafe and cleanses, but if u dont have a high star nihilus i dont se a point on zetaing sidious... Also without Vaders Z sidious dots will be cleansed in the whole team sooooo fast (currently they even cleanse it while zader is active... Bug xD)
Zavage could be a good last man standing... But if u reach the point where only Zavage is alive against a few enemys they will kill him anyway (much faster if he isnt G11-12), and if u reach the point where zavage is ur last man against a single healing rebel... Well u will have to forfeit cuz this bel will keep healing as well as ur Zavage in an infinite loop xD
Zylo? Maybe but have in mind a full First order team really sucks in DS TB... I tryed a team with Daka, ventress, kylo, RG and EP and they worked surprisingly well xD (all G8-9 but ep G11) this insane stun keep enemys from moving usually... And when someone got low heal RG taunts, when someone dies Dhaka revive xD it was so fun at early phases (1-2-3-4) and got even 4/4 when i used them xD
They was as a team much better than other of my G11 team in this TB...
But since i had RG to taunt and dhaka to revive i didnt even need the Z on kylo (mine isnt Ztaed) so not necesary either... XD
So IMO dont put a Z in ur toons for DS TB... First of all it was a beta and will change in the next one... And then all u can get from a Z just for TB is a few points... Think if u are lucky and choose wisely maybe u can win just one more battle round a day (i bet u wont xD) so 100k points less a day... Ur guild wont get another star from u by the moment...
So first gear ur DS toons and then try to put a Z in the table, with all those strafe insane aoe a z wont give so much while a ton of protection will make u achieve another round much more times (an a few gear to G9 some toons is way less valuable than a whole Z)
In other hand... Zader and Zylo are so good Zs in other places of the game so its not a bad idea to put a Z on them, just no for the DSTB