While in a match, press F4 > Team Battle League > Join TBL > Spectate
You should be able to see both your team and the enemy team’s lineup if you do this fast enough (or else it gets pushed down the view window by newer matches). As for builds, just do /memberinfo TEAM_NAME in chat.
Yes, Zoomy is still rampant but it’s now just used for non-TBL purposes as more of a QoL improvement for the game especially in PVE. I don’t know if it still works in GvG though.
As @Fuwaro previously said, Dethrone’s range goes beyond the max zoom level in TBL. AFAIK we haven’t heard anything in kTOS about possible change to its range so I guess it’s really intended to be that way. Anyone who joins TBL and complains about getting OHKOed should really reconsider their equipment and stat allocation.