The Black and Whites have the momentum with four straight wins, compared to back-to-back defeats for the Warriors, but Ellis also believes his side will draw an advantage from reaching the final the hard way.
They were unfancied against Catalan Dragons and Warrington in the last two rounds but produced their best rugby of the season to turn the tables on the favourites, whereas Wigan have reached a record-extending 30th final largely untroubled.
Ellis knows from painful experience the dangers facing the favourites, having been a member of the Leeds team that suffered a surprise defeat to Hull in his only previous Cup final appearance.
"In 2005, Hull had had a similar run-in to this year in that they played a lot of Super League opposition, whereas we didn't play hardly any," Ellis recalled. "We played Toulouse in the semi-final at Huddersfield.
"It's probably hardened us up a little bit so we know what to expect when it comes to the final. We seem to have saved our best for the Challenge Cup, it's certainly brought the best out of us.
"Even Wakefield at home was a tough game and then we drew Catalan away, which I don't think anyone wanted, especially after being bashed by them in the league. We had to go there with a totally different attitude and we really dug in.
"Warrington had been playing really well going into the semi-final but we managed to fight for a win and that's probably been the thing about us, we've had to fight for our wins.
"That's when we've been at our best, when we are all willing to work hard for each other and we've got blokes scrambling back to make cover tackles.
"Often that's the difference between winning and losing."
Hull will be without winger Tom Lineham, who failed to shake off an ankle injury which is set to give a chance to Jason Crookes, but centre Ben Crooks is poised to return after missing the last four games with a similar injury.
Long-serving utility player Richard Horne was also included in coach Peter Gentle's 19-man squad before they set off for London.
Horne, 31, has not played since sustaining a foot injury in May but he was out for more than four months in 2008 before earning a shock recall for the final against St Helens.
His call-up provides the only selection dilemma for Gentle, who must decide between the vast experience of Horne or the raw talent of promising youngster Jamie Shaul as the replacement for injured full-back Shannon McDonnell.
"We've picked up a few injuries over recent weeks but that's the way it goes," Ellis said.
"It's funny how things can turn around. Jason Crookes has hardly played this year but now he'll hopefully be playing in a Challenge Cup final."