Freeza being made good shouldn't be possible when his power surpasses that of Porunga's creator. Freeza would kill Dende before he can change the wish and with the time wasted, Goku ends up dying. Mecha Freeza later destroys Earth.
For the sake of the scenario though, let's say it works and Freeza becomes completely altruistic. Goku returns to Earth and Freeza joins him after he's set about restructuring his empire. The future timeline doesn't change significantly as even if assuming Goku got the heart virus from Yardrat, he'd probably be quickly targeted and killed by #17 and #18. Trunks travels in time to warn everyone and they begin training, with Freeza training with Goku, Piccolo and Gohan.
With 3 years of training gains, Freeza quickly gains the Golden form and masters it, essentially making him as strong as his ToP self. Goku, Gohan and Piccolo all become far stronger than their canon selves by training with him too. #19 and #20 are quickly killed and once Trunks arrives, they learn about #17 and #18. After struggling to find the lab, Freeza decides to just destroy the entire mountainous area with the plan to just restore it with the Dragon Balls, though is quickly talked down from doing so when that may mean reviving #17 and #18. After hours of searching, they eventually find the lab and destroy the twins.
When Cell awakens, he is at a loss of what to do and decides to gather the Dragon Balls to revive #17 and #18. With nobody looking on the Dragon Radar, they don't realise what is happening until it's too late and Cell gains his Perfect form. Freeza quickly finds him and beats him to a pulp, with Cell deciding to self-destruct. Without Shunkan Ido, nobody can stop Cell destroying the Earth, though Freeza survives and quickly destroys SPC. He then heads to Namek and uses the Dragon Balls to revive all those killed by Cell's self-destruction and is told to take Dende with him to be Earth's next Kami, the second wish bringing the two back to Earth. He then helps Trunks train enough to gain the strength to destroy #17, #18 and Cell (though nobody is entirely sure who Cell is).
7 years later, the 25th TB occurs. Without many of the main battles in the Cell Arc, Gohan is far weaker than his canon self and follows the same story as in canon. Mr. Satan isn't a major figure due to the Cell Games never happening, so the city isn't named Satan City. Goku and Vegeta are far stronger than their canon selves due to Freeza acting as a major motivator and sparring partner, though Goku likely wouldn't have achieved SS3 due to the lack of otherworld training. Freeza doesn't participate in the Budokai out of fairness, though joins the group when they head to Babidi's spaceship. Freeza easily kills Dabura and destroys Boo's pod, ending the arc anticlimactically.
When BoG happens, Beerus is eventually provoked by Freeza who desires to show his new power. Beerus is impressed, though quickly deals with Freeza to everyone's shock. The SSG ritual occurs and though Beerus is fairly disappointed after having faced Freeza, he concedes to let Earth be in peace. Goku, Vegeta and Freeza then start training with Whis. Obviously, FnF doesn't happen and for the Universe 6 Arc, Freeza takes Boo's place and solos the U6 team after Goku is beaten by Frost. Goku still forms a friendship with Zen-Oh. For the FT Arc, training with Freeza would've probably had Goku and Vegeta achieve PSSB early to keep up with him and thus, the fight with Zamasu occurs far quicker. Freeza kills Goku Black before Zamasu can heal him and though Zamasu's immortality leads to him wearing down the group, Goku uses the Zen-Oh button to end things.
With the ToP, things are near enough the same, bar Freeza's bait and switch with Frost. The Broly Arc never happens and having not had a reason to abandon the Freeza Force, Cranberry never releases Moro.