What is a true Darkseid? Is it the one that Superman beat until he couldn't open his eyes? The one that Doomsday beat into the ground? The one that Superman beat up and shoved onto the Source Wall? Was it the one that the Nu JL blinded and sent packing? Is it the one that fought the Anti Monitor? Who were those guys, and why do people credit Superman for beating half of the ones that I mentioned, if he wasn't the true Darkseid? DC should really make up their minds.
Oh okay. So from what I recall, Darkseid was meant to be an equal to Galactus, but we have rarely seen this version, unless he is the one that fought the Anti Monitor recently? Without high balling or low balling, I would assume that we would compare him to a well fed Galactus. Not quite Megaversal whatever that is, but still very powerful. if that is the case he may defeat Tyrant, but he would have his hands full. I'd really be interested in reading what people that are really familiar with Darkseid has to write on this.
Jack Kirby's vision for Darkseid was to make him a Galactus level being but then hacks like Jeph Loeb decided to write him into Superrmans punching bag, even though Darkseid casually smacks around characters in Superman's tier if not above including guys like Orion, Eclipso, Agogg and even Superman himself on a few occasions. Thankfully Grant Morrison retconned all of it into Avatars
Nu 52 seems to be more in line with Kirby's vision of Darkseid though, since it took the entire League just to BFR him and Anti Monitor himself having to absorb additional universes just to face him.
Huge mismatch against Tyrant: true form Darkseid falling from higher dimensions in FC was causing the Multiverse to collapse on itself, forming a singularity.
Avatar Darkseid vs Tyrant would be the right match-up, even if, also in that case, highest DS' avatars showings would still give him the win IMHO.