Booster Gold is going to seem like their best friend by comparison.

How bad off do you have to be to actively want Bart Allen's help? Let's ask today's guest-stars, the Legion of Super-Heroes, in 1997's Impulse #21, "A Little Knowledge" Written by Mark Waid, pencils by Craig Rousseau, inks by Wayne Faucher.

Bart would also guest in the Legion's own book, issue #88, which featured a cover homaging the Legion's first appearance in Adventure Comics #247; but this issue features another reference to their first visit to Superboy: the Legionnaires, in period civilian clothes, prank Bart by calling him Impulse. Bart does not take it as well as Clark did, since Clark didn't have to worry about zen speed master Max Mercury strangling him...Still, after that's sorted out, Bart is thrilled to see the teenagers from the future, since he assumed his cousin XS would be with them...and she's not. Nor are they there to make him a member: they were trapped in the 20th century, and needed help getting back to the 30th. Cue a flight-ring ride to the Flash Museum! Bart momentarily seems like he was going to leave them to it there, and bounce with Saturn Girl's flight ring.

Despite a brief warning from a ghostly Impulse, and a couple more manifestations, they still let Bart take them to the Cosmic Treadmill, which actually stumps Brainiac 5 for a moment: how is that thing powered? "Well, dur! It's a treadmill!" Impulse demonstrates, and Brainy immediately activates his force-field, causing them to briefly appear a few minutes earlier then return. (To Brainy's eye, even the Flash using that thing would've been unsafe!) Bart can seemingly only travel in a ten-minute window, and when he stops vibrating at a specific frequency, he and whatever he's carrying at the time return to his present. Attempting to show it could be done, Bart puts them all on the Treadmill, but seemingly only transports them to a lab, where a white monkey yelling "Koko!" jumps onto Brainiac 5's head and stays there.

Undeterred, Bart keeps trying, which of course leads to dinosaurs. He's then able to get rid of them, but loses the Treadmill, and the Legion has long since lost their patience. Well, Spark points out, while it was a complete waste of time, at least Brainy got a monkey out of the deal...and as they leave the museum, the Treadmill returns, none the worse for wear. 

The Legion has of course been rebooted a couple times since, and I don't know if XS is still a member, or even still Bart's cousin. That'd be a shame, he'd miss her.