At first, he would be treated as a regular bad guy and get confronted by some mid-level heroes. It wouldn't be until he killed a few, that the big guns would show up.
If Hulk showed up, at first he would get his head handed to him, because he would probably underestimate the newcomer, do to unfamiliarity. Not knowing what to expect, DD's speed and strength and ferocity would catch Hulk off guard. Since you know I am not playing favorites, I think it would catch Thor off guard at first also.
Later fights, once the threat is known, might play out differently, but that is a different thread.
Heroes rarely throw their worst weapons or attacks at a character unless it is a last resort. So, I would imagine that there will be a lot of bodies laying around before the likes of Reed and Pym bring out the shiny devices, or before Hulk starts using his Hulk/Banner/Cunning/Intelligence mix, or before Thor starts using his Solve-Any-Problem-Magic-Hammer tricks.
But, since this would be a life and death scenario, it would escalate quickly.
X-Characters have some heavy threats in the bullpen, but I really don't see any of them that would be able to handle DD at the early stages of the battle.
FF have characters that are either durable enough, shielded enough, or distanced enough to survive the initial melee.
Avengers, though powerful, will lose some people, right along with the X-characters in the beginning.
Stark will go in and initially have his armor peeled off of him. He might live through it, he might not. If he lives, he will be back with something more powerful and tricky.
After waking up, Thor or Hulk will change strategies and any battles with DD will quickly become close combat, feral and very destructive to the surrounding area. I don't think DD will allow time for a bfr, a thunderclap, etc. He does not stand around, posing and threatening as many powerful villains do. He goes right in, again and again.
While all of this is happening, Dr. Strange may be preparing something wicked and Doom may have tuned in on some sort of display out of harms way. Reed will be going through his closet, as will Pym.
In the end, it will probably look something like this:
Ben, Thor and Hulk pound it out with DD as he speeds around them, then jumps in for the attack. They will live through it and keep him busy, if they don't outright destroy him.
Meanwhile, Strange, Pym, Doom and/or Reed will be setting up some sort of game-changer. Doom may be involved, simply because DD could end up becoming a threat to his plans.
Whatever happens after this, will happen on top of a heap of costumed bodies and in the smoldering ruin of a former city, state, or continent.
IMHO. 😐