As a previous poster mentioned, it depends if they're the same age or actual. I wasn't impress by Donna, Garth or Wally when they were young. Both Bart and Cassie have better feats than any of them. I started noticing the original Titans, especially the one's I mentioned when Flash was in the Justice League, Donna came back from her so call death, and Garth gained his mystic powers.
You reminded me that Donna proved too strong for Cassie to contend with even with help upon Donna's return.
No one save Bart or Cassie has a realistic chance against Donna unless she allows it.
However, in character, Donna DOES allow people she is thoroughly superior to in nearly every way to contend with her.
She is strong, compared to all the other fighting characters, even in combination, but she is also supremely gentle.
Most likely Donna would simply neutralize the attacks of Cassie and company effectively enough for the remainder of Team 1 to end the bout with counters.
Maybe it's just me, but with the way you worded that, Bluewaterrider, I'm not sure entirely sure you're aware that team 1 are as they were when they were teenagers, in the Teen Titans.
To my knowledge, when Wally was still Kid Flash he wasn't as fast? Donna had been upgraded before the Reboot as well.