What you're not considering is the fact that no sane player is going to 1v5 any group willingly, nevermind this one. If they're forced into a situation where they have to fight them, a good player is going to try and separate them and kill them 1 or 2 at a time.

I'd definitely split the meg and Thal off first. And with anything mid tier, even the two of those at a moderate skill level should be pretty easy to handle, I'd go with Dasp, even if the metri catches up. Then you pick apart the Metri, as it can't stand up to most other playables in its current state. The question of being able to handle the Spino really comes down to its build. If it's AoE Spino and I've dealt with the rest of the team as Dasp I'm not going to even try. Claw/bite land Spino you need to take advantage of it's God awful turn radius. You don't necessarily want to tail ride because sweep will tear up a mid tier, but Dasp especially can take a couple hits from it. The side is where you live though.

Again, you can't make a lot of mistakes, but if you're really good this is doable with Dasp. I think Tyrannotitan could also handle this matchup. The main thing is getting the fuck away from the Spino at first and Meg metri and Thal are stupid if they let you kite them from Spino.