Strongest mortals in Dragonball Super Manga.

If you follow the Dragonball Super Manga, this should not be a big surprise.

Freeza is the strongest mortal in Dragonball Super, and so far we have seen, no mortal comes close to his level.

In the manga Freeza achieved this power by training for 10 years long a time manipulated dimension called Room of Spirit and Time (ROSAT) on an unknown planet (created by Angel Merus).

Freeza is so powerful, he torpedo'd towards Goku and Vegeta and 1 shotted them at their strongest as if they were nothing. He smiled and walked away, not even worrying about their fusion.

And with Toriyama passed, makes Freeza canonically the strongest mortal under Toriyama's era.

Olderst son of Goku is the strongest on Earth, and if trained and enraged then Gohan without doubt surpass his father.

Gohan always had immense power even back as a kid, greater than anyone else. But this power only shows up when he is angry.

Now that Gohan has learned to mimic his anger, he can unleash his Beast form at will. Thus makes him at least on par with a highly trained Goku.

It is stated in Super Hero arc by Vegeta that they still haven't catched up to Jiren from Tournament Power, despite having similar power level.

Assuming that Jiren kept training, and that he became even stronger.

Jiren's fighting style is like of Ultra Instinct, but not exactly. His fighting style is approved and revered by Whis.

Jiren relax his body, and only increase his power when he strikes. This makes his attacks unpredictable and heavy. To be better at this, the fighter has to train their mind and their ki control.

We don't know much about current Jiren, other than that Goku and Vegeta from Super Hero Arc still have not surpassed Jiren, but hopefully we see him again.

Goku, the main character of Dragonball is surprisingly not the strongest of the show any more but his urge to be the strongest is unrivaled.

There are many fighters Goku has to surpass, and it is unknown whether he will ever be able to surpass them, but he is growing and growing.

Currently he is training Ultra Instinct, and he is doing it for a while and it seems he has still not finished this training. It is said that if he masters Ultra Instinct, nobody will be able to beat Goku any more, as Ultra Instinct has no weakness. Sadly this technique is hard to master, so far only Angels are able to use it properly.

Goku is currently the best candidate to succeed Beerus as the next God of Destruction of U7. This makes Goku indeed a powerful fighter, and obviously a top tier fighter in Universe 7.

Modern Piccolo always lagged behind the others, despite he taking his training serious all the time. As once feared demon king and Toriyama's favorite character, he deserves better. Luckily he got his immense power boost in the Super Hero arc.

Piccolo is now on par with Goku and the others, as stated by Toriyama himself. Piccolo hard work is paid off by his Earth Dragonballs. The Dragon unlocked his potential.. and gave him a "little bit extra power" (Orange form).

In this state he is physically even bigger than before, and has immense raw power.

Regrowing his limbs, elastic strong body and his cunning combat mind makes Piccolo one of the most powerful fighter.

Broly just like Gohan gets his power from rage. But unlike Gohan, Broly is not able to control his rage properly, when he is enraged his behavior is similar to that of a wild Oozaru (Great Ape). This makes him also blinded by rage and attacks everything that moves.

He start to train to control his rage and his blind rage start to be less of an issue, he made progress with controlled Super Saiyan, despite being showed to be inferior to Gohan Beast it is no doubt that Broly is a powerful fighter, and has good potential.