Asking Nemesis Mains How To Play Nemesis?

His tentacle has very unique properties. The way it functions is that it shoots out a bunch of tiny hitboxes in a straight line that start from top to bottom for the duration of the attack. This is why his tentacle in tier 2 and 3 hits survivors vaulting pallets and on the other side of dropped pallets (unless they crouch) instead of breaking the pallet as one of the upper hits made contact with the survivor, and after the tentacle hits a survivor or pallet any further hitboxes are canceled, which is why you can't hit a survivor then break a pallet (or vice versa) in the same swing.

On most maps, you can hit survivors through windows even if they crouch on the other side of it. Currently the only exception to this is swamp maps, as the windows on those maps are unusually just high enough to protect a survivor from a tentacle attack if crouched.

Another aspect of his power is being able to hit over objects similarly to Huntress, Singer, etc. The general rule of thumb is that if you can see a survivor over an object you can usually tentacle them over it unless they crouch in time (however there are some loops with gaps or are so low, such as a handful in the hallways of RPD, where even crouching won't protect the survivor from being hit).

This tip is the most advanced and the most important. Since his tentacle attacks fire multiple hitboxes over a short time, and you can still move during the attack animation, you can essentially "drag" his attack over a wider area by moving to one side or the other during the attack, allowing you to not only get some pretty wonky looking hits, but also allowing you to release a tentacle and hit a survivor when you're turning around a corner earlier than you feel like should be able to, because it looks like you're just going to hit a wall (which the upper hitboxes indeed will), but by facing the right way and then dragging it into the open, the lower hitboxes still have the opportunity to connect.

Now about proper zombie usage. If they happen to be in a good spot while you're chasing a survivor, make sure you take advantage of that to zone the survivor into the zombie. If a zombie is either stuck on collision or patrolling an area with no gens or blinded in a random area, it can be a good idea to hit the zombie (m2 if you still need more infection, m1 if already tier 3 for a shorter attack cooldown) if you already happen to be nearby. However, zombies in general are a piss poor way of gaining infection even if you have add-ons boosting infection gain from them and should really only be m2-ed if you're just barely missing enough infection to tier up. When it comes to using your zombies for tracking, their chasing animation helps you know a survivor is generally in that area but they'll usually be long gone or stealthing by the time you get there so it isn't very reliable. However what is reliable is paying attention to if they've been blinded next to a generator, as that means 9 times out of 10 a survivor is on it.

Lastly, add-ons. Imo, he only has 3 general purpose add-ons; the rest either are horrible or situational and should to be used as part of a build focusing around them. His three best add-ons are: Marvin's Blood, Broken Recovery Coin, and Depleted Ink Ribbon. Nearly every single add-on that affects zombies in some way have next to no benefits; even Depleted Ink Ribbon isn't amazing but it just goes to show that utter lack of useful add-ons. Stealth via Oblivious/Undetectable is difficult, but not impossible, due to his footsteps sounding like miniature earthquakes, giving you away pretty early. Jill's Sandwich + Iri Umbrella Badge is an alright but not great combo, as you can only make use of the exposed effect a maximum of 4 times. I could go on for days about his awful add-ons, but I'll stop there. Your best bet is literally Marvin's Blood + Broken Recovery Coin every game unless you're trying to do a cheeky build.

That's pretty much everything to playing Nemesis. Hope this helps and good luck to you. If you want some perk/build suggestions I can go into that as well in a separate comment if you like.