In the new Dragon Ball Super movie, there’s a good possibility that Piccolo’s power can be on the level of Super Saiyan Blue, the second strongest form in the anime behind Goku’s Ultra Instinct ability. Piccolo is currently far below Goku and Vegeta in strength, but he could narrow the gap when he returns.
Unfortunately, Piccolo stopped being an asset to the Z-Warriors in the Buu Saga, and it wasn’t until the Tournament of Power story where it began to feel like Piccolo mattered again. While helping Gohan get back into fighting shape, Piccolo revealed that his power has been secretly growing for a while now. After that, the character formed a capable tag team with Gohan in the tournament, and actually made numerous contributions to their victory before becoming the fourth member on the team to be eliminated.
There are indications that Piccolo could soon receive a massive on-screen upgrade in the anime’s future, possibly in the second Dragon Ball Super movie. During the Moro arc in the show’s manga continuation, It was stated by Goku that he could hardly recognize the power levels of Gohan and Piccolo, who had apparently grown much in power since the anime’s ending. Exactly how powerful Piccolo is at this point isn’t made explicitly clear, but his battles with Seven-Three and Saganbo in the manga provide clues about his power. He’s confirmed to be weaker than Gohan, but based on his performance, it looks the difference between them isn’t that huge. Also, Piccolo seems to be quite closer in power to Android 17 than originally thought, considering that one didn’t fare any worse than the other during the battle.
Since both Gohan and 17 are strong enough to fight evenly with Super Saiyan Blue Goku, it follows that Piccolo could share a similar level of power in the manga continuation, and now these capabilities can be shown on-screen as well. As for how he could have come this far, it’s known from that story that Piccolo didn’t slow down on his training when the tournament ended. Instead, it would appear that he intensified his sparring with Gohan, allowing both to make impressive gains. So even if the Dragon Ball Super movie takes place before the Moro arc, Piccolo should still be a lot more formidable than he was at the time of the Tournament of Power. And that’s saying a lot, especially when taking into account how well he was able to hold up against the Universe 6 Namekians (who were close to the strength of Ultimate Gohan).
Piccolo being Super Saiyan Blue-tier feels like it would be a well-deserved change for the character. After all, training and meditating are activities that the character has engaged in regularly since the beginning, so it only makes sense for his power to keep climbing rapidly rather than remain stagnant. Plus, it’s been too long since he was anywhere near the top two Z-Warriors. The last time that happened was when he fused with Kami and fought Android 17. But with enough diligent training, Piccolo can rival the Super Saiyan Blue transformation without having to rely on another Namekian fusion. Piccolo didn’t get to have any role in the fighting in Dragon Ball Super: Broly, but that can change if his power improves enough for him to become relevant. If so, Goku and Vegeta may find themselves calling on him for help when the next threat arrives in the second Dragon Ball Super movie.