Cell Max is way stronger than Perfect Cell. Perfect cell was solar system to galaxy level at best. Cell Max was in the low multiversal to multiversal tiers of power. So let's powerscale and confirm this.
Gohan had to access a new incredibly powerful form, confirmed by Toriyama to be stronger than Goku and Vegeta's, to beat it. Unfortunately for Jiren, this implies that he will never get close to defeating Cell Max in a one-on-one fight (with the former being at his Tournament of Power power level).
Cell Max is too much for the Gamma Androids and Orange Piccolo. Only Gohan Beast is strong enough to finish him off. Goku isn't around to take on Cell Max, but his Ultra Instinct energy avatar would be the perfect tool to defeat him.
After defeating Piccolo, Cell absorbs Android 17, which changes him into his "Semi-Perfect" form. In the "Complete Metamorphosis" life cycle of certain insects (like cicadas, after which Cell is actually designed), bugs go from eggs to larvae, to pupae and finally, achieve adulthood.
He was later able to clash with and overpower Great Namekian Orange Piccolo before being completely overwhelmed by Gohan Beast, who easily killed Cell Max after Piccolo held him in place.
Assisted by his father in spirit, Gohan retaliates with his own Kamehameha, ultimately overpowering Cell with Vegeta's help, destroying his cell nucleus and killing him once and for all.
Because Cell has Frieza's DNA, it is theoretically possible for him to achieve this form. To do this, he would need to train his body to the point that Frieza did. He never actually trains at any point in the original series; instead, absorbing others to increase his power.
1 Winner: Goku
Ultra Instinct Goku is faster, stronger, and more agile compared to his opponent and on top of that, there is a significant difference in their respective power levels. By the time Broly increases his power level, Goku might have found an even greater control over Ultra Instinct.
Perfect Cell (Full Power) 2.5 Billion. After the destruction of his Cell Jrs at the hands of Gohan's new Super Saiyan 2 transformation, Cell powers up to absolute maximum. However, his strength is not enough as he is unable to overpower Gohan.
Gogeta IN BASE FORM can bust the universe 40 times over at minimum according to fusion math and I highly doubt Cell Max was that powerful. And with this much firepower against an opponent that large, Cell Max would've taken every single one of these and got severely damaged.
Toriyama himself confirmed that if Cell Max had been completed as per the plans, he would become a being that even Broly couldn't defeat. But, as he doesn't complete his Cell Max form, he stays beatable even after becoming an uncontrollable monster.
Cell Max was a Bio-Android created by Dr. Hedo for the Red Ribbon Army to aid them in their goal of world domination. The design of Cell Max was based off of the blueprints of the original Cell, albeit he was far stronger than his predecessor.
While in Dragonball Super: Super Hero, Cell MAX is a screaming mindless monster. This is largely thanks to his Brain Patterns not being fully complete thanks to Meganta releasing the Bio-Android per-maturely. He's shown to have intelligence in speaking full sentences in the DevilArtemis Universe.
Unfortunately, the difference in power between Beerus and Frieza is immense, meaning that there's simply no way that Frieza can overthrow this permanent thorn in his side.
Ultra Ego Vegeta presents the Saiyan Prince at his best, but Black Frieza doesn't struggle to take out both Ultra Ego Vegeta and Ultra Instinct Goku in the same strike. For once, Frieza has completely surpassed his Saiyan nemeses.
Nothing, because Cell physically can't absorb #16. The only reason why Cell could absorb #17 and #18 in the first place is because most of their modifications were bio-organic in nature. They had almost no mechanical components.
There is a reason not Even heroes will ever show beerus losing or even struggling. Even TOEI knows beerus is still supposed to be stronger than any mortal we've seen so far. Beast Gohan may be the strongest mortal in the multiverse we've seen so far but Even he is probably nowhere near beerus.
They had to fuse into Gogeta to take down Broly, showcasing the character's power level. Gohan Beast's power level has been stated to be above or at the very least close to that of Super Saiyan Blue Gogeta, making him strong enough to take on Broly. At their current power level, Broly can be defeated by Gohan Beast.
Cell MAX was designed by Hedo based roughly on Gero's schematics, but he is NOT just Cell 2. He is a complete creation in and of himself, and was UNFINISHED, not IMPERFECT. He would have been what he was regardless of whether or not Hedo had time to finish him. He simply would have been less of a rampaging monster.
How would that influence the rest of the series? The universe would implode because he would have reversed Akira Toriyama's decree of Vegeta never being allowed to beat a villain.
He knew that Gohan had the power to surpass him and take down Cell once and for all. Giving Cell a Senzu Bean to let him fight at full strength meant that Gohan would have to give his all during this challenging battle.
Buu eventually awakens and is taken to New Namek to confront Moro. During the fight, the Grand Supreme Kai takes control of Buu's body and it's revealed that Buu once had god ki, but it was destroyed when the pure Majin Buu was killed by Goku.