Evil Vegeta said:
Trunks said the difference between the Androids and himself was huge right after fighting them. I think that's enough to conclude he was much weaker than them.
Also, Freeza plowed through a KMHMH that Goku was apparently using to finish him. I wouldn't call Freeza powerless prior to his stamina burning out. A better example would probably be Vegeta Vs #18. He was able to hang with her for awhile, but ultimately proved to be powerless since she was ignoring his attacks and his own stamina was going down.
Whatever fight Trunks believed he put up couldn't have meant much.
I am aware, I was talking specifically about the line GreatSaiyaman posted, in which according to VIZ it's stated he was powerless against him.
Moreover, the difference could lie on that being [Mecha saga] Trunks, and the Trunks who has made the later statement being the one from the androids saga. As many could argue, Trunks could have gotten strong enough to now be able to fight them decently well, whereas himself from 3 years ago just paled in comparison to them. Something like "Future androids > Trunks (androids saga) >> Trunks (Mecha saga)".
I am aware that the line is a little different on the original though.
As for the Freeza's example, well, if Freeza was weaker than Goku, then I'd call him powerless. That's what I define as powerless, lacking in power to fight on par with the opponent, be it by a stomp or by a close fight. Maybe the 22nd Budokai in which Goku and Tenshinhan fought is also a good example. Tenshinhan was powerless against Goku, yet he was able to give the boy a good battle.