Dwynen

Hey, my dude, Josh and Howie here. Glancing at the deck a couple things come to mind.

Firstly, it looks like you are moving in the "play a fuck ton of elves" direction. This is super cool, but often times is helped by adding another color. I know you were talking about building a mono-colored commander deck, so if thats the point here, thats cool, but if not, look at Rhys, the Redeamed; Elvish Abomination (commander legends); or Ezuri, Claw of Progress.

Alternatively on that point if you are trying to keep it mono-colored, maybe look at Freyalise, Llanawar's Fury or Marwyn, the Nurturer as the commander.

Secondly, i'm noticing that you're trying to include a +1/+1 counters subtheme within the deck. I think this is a dangerous road to go down. If its facilitated by your commander (Like if you were running Ezuri, Claw of Progress or Marwyn) then you might be able to get away with it, but without commander support, you'll likely find yourself with a bunch of cards that don't work with each other in your hand. It can feel like youve smashed two different decks together and are trying to play them simultaneously.

On that note, cards like Pollenbright Druid, Gladehart Cavalry, Cultivator of Blades, the Ozolith, Battlegrowth and Inspiring Call are only good in a deck with a lot of synergy to support them; they aren't self sufficient. I would cut those cards unless you plan to switch commanders to something that better supports them. Even if you do switch commanders, they still may not end up being good enough.

A caveate, cards like Realm Seekers and Elvish Vanguard I don't include in this list, because their +1/+1 counter interaction doesn't require outside help to be effective. They make their own counters and are their own payoffs. Because of this, I think they fit in your deck much better and should not be cut.

Similarly, you are running a couple of cards that seem to fit in different strategies that don't have enough support in your deck. For the same reasons mentioned above, I would look to cut Nissa, Vital Force and Elvish Pioneer. These cards are more aimed at a "Lands Matter Strategy". I would also look to cut Season of Growth, as you don't have enough spells that target your own things to make good use of the second clause, which is the far better part of the card, and Eidolan of Blossoms as its more aimed at a "enchantress" strategy your deck currently doesn't support.

Thirldy, there are a couple cards that just seem inefficient. I would look to cut Untamed Might because there are far better ways of taking advantage of large amounts of mana or making your elves massive (i.e. Craterhoof Behemoth, Overwhelming Stampede, Overrun, Triumph of the Hordes, Finale of Devestation, Thunderfoot Baloth, etc.). I would also cut Abzan Beastmaster because, with a number of small creatures in your deck, i think you will struggle to trigger the ability, and Elvish Eulagist, because a bunch of life on a one time effect that is reliant on you having a large graveyard is simply not as impactful as a Fog, or better yet, a way of protecting that board from ever filling your graveyard like with Heroic Intervention.

Finally, I think you need a few more ways of helping you finish off games after you've built your big elf board. Growing Rites of Itlimoc and Gaea's Cradle will help you make crazy amounts of mana; Regal Force, Shamanic Revelation, and Collective Unconcious (as well as Return of the Wildspeaker and Rishkar's Expertise if you switch to Marwyn or Ezuri as your commander) draw a ton of cards to refresh your hand after building a board; any of the cards I mentioned previously to make your creatures big; and/or Joraga Warcaller would make great additions to your deck. Another good option might be Champion of Lambholt, which isn't and elf, and takes a few turns to get going, but can help get your attackers through block-y boards.


DAMN THAT WAS A MOUTHFUL!

In all, I think the deck concept seems awesome, I'm excited to see how it grows. I like the direction and I hope the above suggestions will help to steer you in the right direction moving forward.

The Skinny of it:

1. Think of switching to a different commander. Either to gain a color or to improve utility in your command zone.

2. Avoid side strategies! They are hard to build and very punsihing when done poorly.

3. Avoid inefficient or low-impact cards. In a singleton format you need all of your cards to be worth playing in a number of situations.

4. You're doing a good job finding cards that make the deck run. Look for ways to turn that into a win!

CUT:
Pollenbright Druid
Gladehart Cavalry
Cultivator of Blades
The Ozolith
Battlegrowth
Nissa, Vital Force
Elvish Pioneer
Eidolon of Blossoms
Season of Growth
Untamed Might
Abzan Beastmaster
Elvish Eulogist

ADD SUGGESTIONS:
Craterhoof Behemoth (Finisher)
Beastmaster Ascension (Finisher)
Triumph of the Hordes (Finisher)
Overwhelming Stampede (Finisher)
Overrun (Finisher)
Finale of Devestation (Finisher)
Thunderfoot Baloth (Finisher)
Joraga Warcaller (Finisher)
Champion of Lambholt (Finisher)
Growing Rites of Itlimoc (Mana)
Gaea's Cradle (Mana)
Regal Force (Draw)
Shamanic Revelation (Draw)
Collective Unconcious (Draw)
Return of the Wildspeaker (Draw)
Rishkar's Expertise (Draw)

If you search for the decktag: two-headed giant
You will find a list of what others have made.
If you and your friends start to use the tag you will probably revive interest in the format and it's easy to find all the decks made recently.

Northernwarlord is currently active, and has posted EDH giants in the past.
Maybe the 4 of you can strike up conversation ?

I've also noticed that some two headers use the tag: thg

Will you inform your friends, or shall I do it ? ;)