Stranger Things '85 cannot possibly be canonical to the life action series
As the title says, having watched Stranger Things '85 I don't see how it can possibly be compliant with the live action series.
The kids in the show are able to fight off plant/demogorgon hybrids on their own, mostly using a bunch of gadgets that Nikki makes for them in her garage.
By the time the first season ends, these kids have experience fighting monsters way beyond anything we see in season 3 onwards. For crying out loud, Nikki builds a fuckin laser-cannon capable of severing the limbs off of a giant demogorgon/plant queen.
If Stranger Things '85 is cannonical, the way the kids act in season 3 would make no sense. They would be waaaay too experienced in fighting monsters to act the way they do in season 3. For example, when Billy is choking the life out of El, there is no reason at all why the rest of group would just cower and only Mike would have the cajones to intervene. The enemies the kids fight off in Tales from '85 make flayed Billy look meke by comparison.
I know Stranger Things '85 isn't going to directly contradict anything that happens in the latter seasons, but the notion that this could possibly fit into the live-action timeline is just bonkers.
Don't get me wrong, this show is very enjoyable for what it is but I can't see how anyone can watch it without considering it an alternate universe.
EDIT: And just to add something to this, the "gadgets" that Nikki makes are absurd.
It's not just that Nikki has a laser canon, it's the other stuff too.
Nikki also has a chainsword (something straight out of 40k)
Dustin has what appears to be two canons on each arm that fire out flaming plasma balls!
Lucas? -> The slingshot from hell. It might as well be a pistol.
Will? --> Nikki outfits him with what looks like a power axe.
Max? --> Projectile buzz saws
Mike? --> The hockey stick with blades on both sides; all he needs now is the hockey mask and he can be a kid-friendly Jason Voorhies.
These kids have gear that is more effective than what the military has in the live action show, and all of this stuff is made by a 14 year old punk kid.
The cartoon is wonderful, don't get me wrong, but it should definitely be its own thing.