If speed is equalized I'm thinking Tyranids due to the reasons I stated earlier, those being greater intelligence, greater numbers and greater adaptability (something which Gems, especially ones from Homeworld, often seem to lack).
I was just looking through the profiles, and I'm honestly not that sure how Gems stand a chance here other than speed, and that seems like it would only be so useful against such a massive numbers difference. The Gems are described as having between billions and trillions of Gems, of which anywhere from tens of millions to billions are military Gems, whereas Tyranids are stated to have likely quintillions of soldiers and/or ships, with invasion forces made up of billions or trillions of organisms, and it was stated earlier this was the entire Tyranids species vs the Gems, meaning they will have quintillions of troops. Even if we're extremely generous and say the Gems have 100 trillion troops and the Tyranids have only 1 quintillion that still leaves us with 10,000 Tyranids to every individual Gem, and Tyranids weapons are high 6-C, while Jasper, whom was considered to be the perfect example of a type of Gem specifically designed for combat, is marked as 7-A, meaning they should be able to damage the Gems just fine, and with that many troops (the difference in which is likely much higher, as it's stated on the profile that Tyranids have quintillions, as in multiple quintillions, whereas Gems are stated to have billions to trillions, not all of whom are designed for combat) they get a lot of chances to try and get a hit, especially as dead Tyranids can be reabsorbed and used to make new ones. Let me put it this way; you as a human can probably kill a rat just fine, especially if you're way faster than it and have a gun, but if you are facing 10,000 (or more) rats that all have guns, that are controlled by the powerful Ratmind, and that are gunning to kill you (and likely have a pretty good idea of how to do so after the last few battles with humans, which the Ratmind told them about), and they can make more rats from the corpses of the other ones, you're probably going to die. This is on top of Gems being very slow to adapt and change whereas individual Tyranids can make slight changes on the fly, and newly created Tyranids typically carry new evolutions.
Finally, assuming less generous numbers then if Tyranids have 2 quintillion and Gems have 2 trillion soldiers then the numbers difference becomes 1 million Tyranids to every Gem, and if we use the figure that assumes a few billion Gems are soldiers it gets worse. While the profile said that Tyranids typically invade with forces between the billions and trillions as far as I could tell that was individual invasion forces, whereas the entire species (which is being used here) is made up of quintillions of organisms. Tyranids are also described as working in perfect synchronicity when synapse Tyranids are there to control them, so they should be more efficient and effective than Gems as well.
ontTalk/Durability_required_to_resist_the_heat_of_the_su
