User blog comment:Dtregle/Jason Todd in Young Justice/@comment-5154078-20120617232957/@comment-26880654-20120731002327

I guess Jason became Robin right after Dick became Nightwing and became part of the Team for a short while but later quit due to his way of dealing with criminals.He died 2 or 3 years later(Considering Dick turned Nightwing one year after the season 1 ending and Jason died with 13 or 14 years old) and he came back to Gotham 2 years maximum after his death.After Jason fought Batman(And maybe Nightwing) Batman recruited Tim to be the new Robin and they never told him about Jason making him believe he was the 2nd Robin.

Aquagirl/Tula joined the Team in a indetermined time before the second Season and died in the one year before.

Garth/Tempest may have joined at the same time as she did but left the team soon after her death.

The other ones may have just been other Justice League members who entered the League between the five year gap or maybe other members of The Team that we never heard about.