Dragon Ball Z packs a cast of world-breaking martial arts and some characters with universe-ending abilities. Comparing the magnitude of strength to other anime can seem like pitting a lion against a house cat. The villainous and merciless Frieza is high in the category of planet-punching powerhouses.
If Lord Frieza were to stumble into the universe of My Hero Academia with the intention of causing brutal destruction, it would be up to the pro heroes and the students of the academy to put a stop to his senseless violence. However, they would certainly have their work cut out for them. The sheer overwhelming physical strength, speed, endurance, regeneration and destructive capabilities of Frieza’s Death attacks put anything shown in My Hero Academia to shame. That being said, all hope may not be lost for Deku and his companions. The heroes specialize in overcoming the odds and fighting their way to success, even when the outcome looks bleak.
The combination of the strongest pro heroes would likely be able to entertain a brief skirmish with Frieza’s First Form. A peak All Might and Endeavor combination team would put up the best defense they could muster. With All Might’s One For All having the power to level city blocks to counter Frieza’s martial arts strikes and Endeavor’s Hellflames containing the Death attacks, they would be able to entertain the initial threat. Unfortunately, should Frieza decide to evolve into his Second Form, their struggle would be swiftly squashed.
There are a few other options in the arsenal of the heroes but unfortunately, they rely on particular scenarios to be of any use. Should Eraserhead use his Erasure on Frieza, there is no guarantee it would affect the alien warrior, as it blocks Quirks. Hawks' craftiness and Fierce Wings could potentially carry Eri within arm’s reach of Frieza to initiate her Rewind, to turn the invader back to dust. However, her lack of control makes such a move risky. In a future timeline where Eri has developed her power, she would be more effective, but as it stands now, she would be little more than a liability for the other heroes to protect. In fact, the majority of the students' powers would not put a scratch on Frieza’s Pyscho Barrier.
When power does not push through and tactics can be swiped aside with minimal effort, there is always the path of deception. The dark horse of the academy is in a prime position to take advantage of a weakness many anime characters have, and Frieza is particularly at risk of such a weakness. Frieza suffers from the condition of talking too much. His arrogance in his abilities and amusement toward those who are pitiful in comparison to his power tend to cause him to run his mouth a bit too often. Hitoshi Shinso is, in actual fact, a strong counter to many anime villains.
In all likelihood, Frieza would see Shinso as little more than an ant in his path -- the student's power level would likely be low, and his demeanor would not carry an air of dominance. All Shinso would need is to be close enough to ask him that fatal question, to which Frieza would be unable to refuse to answer. Ochaco Uraraka’s Zero Gravity could raise Shinso to the likely floating Frieza and bring him into earshot. If the rest of the heroes are defeated at this point, Frieza’s curiosity about what their last-ditch effort would be might give him pause in simply using a Death Canon on the weightless student.
The telekinesis and overwhelming willpower would do very little to hinder Shinso’s Brainwashing Quirk. Once the alien lord was in the trap, he would lack the shonen hero plot protection to break out of such a technique. Shinso could send Frieza back to his own universe, or if he is feeling particularly vengeful after the death of his fellow students, have him Death Ray his own skull.
In conclusion, if Frieza wanted to destroy the My Hero Academia world, he could whip out an Earth Breaker and watch it burn. However, his drive for conflict and desire to arrogantly dominate his foe before wiping them out would be the only chance the heroes would have to make a stand. In the end, it would depend on what mood Frieza was in to determine whether he would accidentally stumble into an embarrassing defeat.