Be serious

"Nice to meet all of you. I'm Tiger-Man as you heard batman tell you guys. I'm here like you guys to stop crime in the world." and get notice by the Justice League.

"That an honorable cause, time to see if you have what it takes. You'll be with Superboy and Raven on this upcoming mission to stop three of the known villians of Killercroc, Bumerang Guy, and the newist villian Dagisth a mad scientist that came out of nowhere. We don't know what they are up to, but we believe that you guys will figure it out. Now time to suit up." said Nightwing.

40 minutes later in a warehouse in Gotham

"Stay down Tiger. We will stop them."

But you already knew who was the mad scientist.