If you have 2* champs but aren't going to compete in the 2* arena while this Ultron event is on...
use Greg's method above to find drones (and maybe Ultrons, but 2* drones for sure at 40 points each).
Basically enter a team of 3 into the 2* and check the choices for opponents. If Ultron or drone isn't there, back out (lose your 0 win streak) choose another team and search, cycle through all teams, takes a few minutes plus the one or two drone matches you'll find.
Don't bother doing this, it's a waste of time. 40 points isn't worth anything in this tourney. The way Kabam has set this up is super tilted to people with 4 star champs being able to fight the 4 star Ultrons.
As a clan we'd need to kill 2200 2 star drones every hour for the entire 7 days just to reach the 4 star crystal.
We'll be lucky if we reach the 75 unit level before the end unless they change stuff and make it easier to get points.