Story's in comments.

The Spartan,the Pilot and the titan

Here's what I think would happen if the titan fall universe was fighting in the halo universe.

I think that titans would be really useful in ground combat due to their durability,strength and their weapons. But they aren't exactly the fastest of mechs or the most agile for that matter.

A vehicle like a Ghost or a Warthog could give a titan a struggle due to their speed and better mobility but they would give them titans some trouble but they would get destroyed.

The main threats would be ether a Wraith or a Scorpion tank. A Scorpion tank would punch a hole right through a titan in one shot,a Wraith is basically the Covenants version of tanks but their cannon is more of a catapult but it's still capable of killing a spartan in one shot just like a Scorpion tank would.

But in a space battle,the milita or any faction in tht titan fall universe are gonna stand no chance against the MAC turrets or the ships the UNCS have. MAC turrets would punch a hole right through any ship or just completely destroy it completely in one shot,any ship the titan fall universe can offer and at infinite range too.

If they went against the Covenant then they would stand even less of a chance but it wouldn't matter. If the UNSC struggled against the Covenant at first then the Titanfall Universe is going to be crushed under the Covenants might.

I think a group of spartans would take a titan down but they wouldn't do it without any issues. Spartan's are basically humans tanks and Titans can be harmed by bullets from regular firearms.

Their ammo is more advanced then regular firearms

But against a scarab or a mammoth,the titans would stand absolutely no chance against ether of them.

A scarab would be way too durable,powerful and are practically invincible unless you destroy its power core inside of the Scarab which is going to be a nigh on impossible task for any pilot,no matter how skilled they are.

Its because the Elites would make mincemeat out of pilots because the Elites are on par with the Spartans on strength and durability in some cases but no matter what,their just way too strong and powerful for a pilots to take down and have much more advanced technology like the energy shields their always wearing while pilots are just puny humans with mediocre armour compare to them.

A mammoth has a mini MAC turret,do I really need to say any more? And their practically indestructible and Titans would be crushed under its weight but that would be highly unlikely likely due to how slow they are.

Well,in conclusion I think the titan fall universe would have a good run but in the end their downfall would be at the hands of ether The UNSC or the Covenant or good grief,the flood.

Do I need to explain how fucked the titan fall universe would be if they encountered the flood? If the flood infects a titan pilot then the flood is going to have all the knowledge,wisdom and skill the pilots had and eventually corrupt the titans and use them as their own.