Or the raid boss could be tied to difficulty. Engage him in Adventure or Skirmish, and it’s still a tough ordeal but it’s doable. Engage him in Guerilla, and it requires a group of two or more.
Offset by giving better rewards the harder the difficulty, but make sure each reward given is guaranteed, and unique to that difficulty level.
Is the requirement based on the difficulty of the machine (e.g too tough to take on alone) or based on player count (e.g on Guerilla, you have to have two or more people, else-ways, the machine doesn’t spawn or you’re denied approaching and engaging it)? 
Like @SR_Carni said, it would require another player to circle around and look for weak spots, or something similar. Like, the Machine would get additional abilities depending on the difficulty. Feels like it would flesh out Guerilla mode some more and not just give it increased health.
Yeah… i don’t think this kind of mechanic would be added to the game.
If solo play is completely removed from the game, then yes, i can accept this co-op exclusive mechanic. But until then, i’m against it.
Edit:
Luckily, i’m not alone with this. Björn, the Lead Designer also thinks like so, after he answered question of possible raid events in the future, in one of the older dev streams, at 00:49:50,
link: https://www.twitch.tv/videos/513977552?filter=archives&sort=time
Well, you never know what the future brings. I for one wouldn’t mind some more group-related content, as long as it remains optional.
Yes, there could be more co-op content, as long as it is doable by solo as well. Best example: The Resistance mission in Himfjäll. Latter is designed as co-op mission and is advised to do it in co-op but it isn’t co-op exclusive.
It is the exclusive part i don’t like. If there would be some co-op exclusive content in the game then i’d expect seeing solo play exclusive content as well, where you flat out, can not do it in MP game and you have to be in your solo game - to balance the exclusivity out.
Yes, I absolutely would deny solo player that loot^^ That’s what raid content is about and I’ve always loved doing raids with my clan back in the day
Your gaming experience with you clan outweighs mine (and any other solo player in that matter) as of why?
I never said that. In fact, releasing a raid boss wouldn’t affect your playstyle at all. You can just not play it. Nobody ever complained about Destiny 2’s raid content only being available to groups, even though it’s even worse there because in GZ, you can just trade someone for the gear you missed out on
That kind of statement causes big trouble.
E.g in current state of the game, with hellbent harvesters spawning in endless amounts of hunters, one could easily say: “You can just not engage harvesters and it wouldn’t affect your play style at all.” 
Careful here, since internet is big and wide and i’m good at Google-Fu.
Speaking of that;
That should do for now.
All what i’m asking is equality between solo and co-op players. As of why you think that only co-op players can experience it while completely leaving out every solo player - that i’d like to get an answer to.
I’m a co-op player. I like challenges that I have to do with my friends, relying on communication and teamplay. This is something I would like to see in the game ¯\(ツ)/¯ maybe there is content that can be released that favors solo players over groups.
So, back to the topic.
Fast-flying Machines would be cool. Or some kind of naval unit to keep players on their toes when they’re near water like, ocean-side.
I think a humanoid/android machine would be awesome. It could track the player across the map, and possibly follow you indoors. I think it would add a little creepy-ness for the late game players. It could either break through windows to get you, or open doors.
Some have mentioned humanoid type machines, but I greatly enjoy the industrial robot feel of the current machines. Think about some of the largest industrial machines in existence, and you can imagine just how insane something like this in robot form can get in a game. Industrial robots do not fly, and I feel the current Seekers are perfect.
I enjoy looking at a current robot and seeing how “plausible” it is. I will sometimes spend minutes looking at a robot and seeing all the bits and pieces that make it work, and I think that is what the devs went for. Machines that look more plausible and less fantasy.
The industrial feel of the enemy is exactly what makes this enemy the enemy, and any futuristic looking type robot would simply kill the ambiance. I feel what we need are more of these industrial machines of the same type of the amazing ones currently in the game.
I think that’s definitely what the devs are going for, the more rough industrial look. It fits the timeline and makes the Machines look more menacing at the same time.
That would be cool to top a hill and see a huge monolithic structure like that stretched across a field or body of water building a base of operations or factory for the machines. Would make for a good raid or random mission to pop up on the map at random. Would keep the game going while other islands or stretches of land are being worked on as dlc or sumtn
I agree with what you saying, and I definitely don’t want this game to lose it’s style. But I think they could pull off a humanoid machine if they did it right. Just look at some real world examples!
https://ichef.bbci.co.uk/news/410/media/images/80418000/jpg/_80418523_f6404d39-48cd-48bc-9370-6a4fabb54caf.jpg https://www.wuwf.org/sites/wuwf/files/styles/x_large/public/201312/5Atlas_post_me.JPGThese machines kinda have a GZ look to them. Change a few things up, and add a new paint job, and I think they would fit in well!
I’ll admit that 2nd one would fit in! Like a Hunter’s child lol.
Perhaps a water-based enemy could be present?
This is a really good idea…! Like a new enemy called a ‘shark’ of something… just ideas!
