#18 is also implied to be below Weighted Piccolo (post-Kami) by #16 and #17, so there's a fair room of difference. #17 didn't outright state that she couldn't handle them, only implying that it may become far more difficult for her, plus he never said the same about himself (though that's likely due to his arrogant attitude).
I'd give this to Piccolo. As suggested by FnF, Goku and Vegeta have poor team co-ordination even after the Boo Arc, so Piccolo could likely just pick them apart one by one. His Gekiretsu Kodan doesn't seem to take much longer to charge than a powerful Kamehameha too. No point in mentioning about Gohan, since he's just fodder here.