I know that you haven't been debating as often as in the good old times, but I understand that you are still a worthy opponent, especially more than LittleCookie08.
Since Peach has had more experience with colder temperatures and she is brighter on screens, plus more attractive, she meets both definitions of being hot; being warmer in temperature and being attractive.
Let me first refute the "Colder" part of the sentence.
1. I did not say her internal temperature, but on average. I agree that Peach is warmer in the guts, but she is less hot on the skin. Let me give you more evidence.
Peach goes to snow kingdom, as to this image
. On the contrary, Zelda never goes to Hebra. These places are the coolest within the map. Click this to see the video
As that this is a debating website, everything shall be backed with evidence. I understand that Zelda may have gone to these cold places, but otherwise, there is a lack of evidence. A lack of evidence means it can be deemed nonexistent. Dinosaurs could have roamed in the base of Empire State Building, but a lack of fossils would make it deemed not true. Again, you HAVE to prove to me that Zelda went to Hebra because those are the places that she should have went to be less hot.
Just to make it clear, Rito village is the most un-cold place of Hebra, so it doesn't count.
Memory 2 suggests that Zelda went to Goron City. Goron City is a hot place. Going there means she is hot at one point, especially with a lack of flame breaker armor(and no, I know death mountain back then isn't as hot, but it is still not cold).
The memory with Urbosa and the one with the Yiga Clan made it clear that Zelda went to Gerudo, also a pretty hot place. Going to these two places means Zelda is hot at some point 100 years ago. This is minus my last point, where Zelda's daily exercise is slaughtering monsters around the malice that burns.
Again, peach does appear in a place that does have something similar to malice, Lost kingdom, but she doesn't have the monsters' heat nor the movement. She just kind of hang out there and stand there. Luncheon kingdom, the same. Peach is always standing in a place where the least heat is transferring. You might say that Peach has a higher internal temperature, but the fact she is afraid to face the temperature of the malice makes her skin, well, less hot. No matter how cold the internal temperature is, as long as the external temperature is hot enough to bring up the average temperature, that one will be hotter.
Who is hotter? Zelda. Exercise, Monster heat. Malice. External temperature is MUCH higher than Peach's. Exposed to as much heat makes your "Zelda's internal temperature" false. Zelda had been having heat for about 100 years. Peach's external temperature is low enough to make her comfortable in her 64-bit castle, but Zelda is fighting for her life every single day, signifying there is danger and the heat is difficult to handle. On the contrary, Peach had never shown discomfort for the castle's lava exposure, which means she experiences less of the hotness. So this either means:
1) Peach's castle environment is less hot than Zelda's Ganon castle;
2) Peach is less hot internally, meaning her internal temperature is less than Zelda.
Zelda has more discomfort handling the heat, meaning that either her environment is hotter, or her internal temperature is higher. Either way, she is hotter, physically speaking. The one who has more discomfort handling the heat is hotter, simply.
In terms of attractiveness, Peach is hotter than Zelda. Peach looks more attractive. She has a smaller waist, and tends to give off a happier disposition, 2 attractive traits in females.
While I don't disagree about the smaller waist, the bright-colored dress she always wears is reflecting light more than Zelda's dull blue shirt. Peach's dress covers less skin than Zelda's tunic. Peach had less absorbed light(she is also whiter, which don't you dare to call it racist), meaning she is relatively less hot.
Your source is Super Smash 4, which uses not the Breath of the Wild Zelda, but the Twilight Princess. BotW and TP Zelda are two different things, having different character models with different articles of clothing.
This image shows one attractive point of BotW Zelda. You agreed to use BotW Zelda as canon. In the picture, it is shown that Zelda is hot by having a bigger butt. The "Press A to Mount" meme came from here.
Now, an actual survey.
Internally(not just a good butt), Zelda is better, being able to be a leader. Peach is a bad leader because she can't even afford to get herself security to prevent Bowser. Zelda is better, with the potential to fight at least one divine beast, and even to fend off guardians. Peach can't do that! Peach is dependent, bound to Mario, and Peach is much weaker compared to Daisy and Zelda consider Peach didn't dare to even lay a single finger on Bowser.
Peach is not that much of a great girl. She is canonically caught cheating with Bowser(hence there is that one good Mario Kart character: Bowser Jr.). Zelda's loyalty and even faith in her love interest(Link) wins. Zelda is responsible. In the times of the war, she stands up to Ganon. Peach, on the other hand, is just plain anarchy and Mario is the one who provides the main political, physical, and every other aid for the kingdom, and Peach doesn't recognize Mario's ability. Mario can easily be a king or prince but nope! Mario to Peach is just a peasant and servant to her.
1. Zelda has more pain dealing with the heat, meaning her temperature is higher, or that she is hotter.
2. Zelda has more qualities to be considered "Hot" than Peach. Peach has many qualities that are not hot.
The rest is up to you.