PDH Vs EDH
First, you need to consider your commander.
If your commander is a legendary uncommon creature, you will not need to ask permission to play your deck in EDH.
If your commander is not a legendary uncommon creature, you will need to ask your opponents’ permission to play it in EDH.
Regardless, everyone should discuss their decks before playing. PDH, also known as Pauper EDH, is at a natural disadvantage, and discussion could lead to a better play experience.
Most of the disadvantages Pauper EDH decks face are because of the format’s rarity restrictions. Uncommon commanders are often not as powerful as higher rarity commanders, and a deck of commons cannot be as powerful as a deck of cards at any rarity. To demonstrate these facts, let's examine some cards.
Soon after being cast, The Beamtown Bullies can eliminate an opponent, and it only takes one card to set it up.
For example, Entomb puts Leveler in the graveyard, and The Beamtown Bullies give it to an opponent so they lose on their next draw. Being able to eliminate an opponent soon after you cast them, and needing only one other card to set it up makes The Beamtown Bullies powerful!
To eliminate an opponent, Mr. Orfeo, the Boulder needs a creature to attack. Because he doesn’t have haste and has a low base power, he relies on multiple cards to be effective.
For example, doubling the power of an attacking Kiln Fiend with Tainted Strike cast on it. If an opponent can’t block, they’ll get 10 poison counters and lose. If all of your opponents can block, cards like Fling can help finish one off. Needing to attack, and relying on multiple cards makes Mr. Orfeo, the Boulder less powerful than the Beamtown Bullies.
Beyond uncommon commanders often being less powerful, the biggest disadvantage of Pauper EDH decks comes from all the other cards being commons. Higher rarity cards are inherently more powerful. It usually takes much more mana, or multiple commons to match the effects of a higher rarity card. That is, if they can match them at all!
Sol Ring is the most played card in EDH. It generates more mana than it costs, and it can use that mana right away to cast other spells. The speed of Sol Ring and other fast rocks accelerate EDH decks far beyond anything Pauper EDH ones can match.
You can get the same effect at common, but you have to pay three more mana for it. That is a huge difference in speed! With such a high mana value, Sisay’s Ring is too slow for most decks.
Big spells are what define EDH, and Craterhoof Behemoth is one of the most infamous ones. It can eliminate an opponent with only a few creatures on board, and the bigger the board, the more opponents it can beat.
In Pauper EDH, there are creatures that give evasion when they enter, creatures that give pluses when they enter, and creatures with large bodies, but there are no creatures that combine all three. It will take multiple commons to create a similar effect, but they likely will not match the efficacy.
Cyclonic Rift is the most obnoxious board wipe in EDH! Returning only opponents’ nonland permanents to their hands is an amazing effect, and doing it whenever you want is super powerful! Cyclonic Rift is more of a win condition than a board wipe though.
There aren't many board wipes at common, but most of them are damage based and hit all creatures. Since there is a lack of board wipes in Pauper EDH, it’s hard to stop opponents from developing a big board. There aren't any commons that can match the effects of Cyclonic Rift at all.
The majority of uncommon creatures, and commons are designed for draft, but most cards designed for EDH are rares. So, trying to match the power of EDH is something Pauper EDH decks will always struggle with.
If a Pauper EDH deck had to play against an EDH deck 1 v 1, the EDH deck would probably win every game. Fortunately, EDH is not a 1 v 1 format, and the self-balancing nature of its games open up opportunities for disadvantaged decks to win. The most threatening decks tend to get eliminated first, and because Pauper EDH decks are usually less threatening, they tend to survive late into the game. After all, it just doesn’t make sense to take out the weakest deck first!
However, being the weakest doesn’t mean that Pauper EDH decks get to win for free. A lot of them need their commander to win, so needing to resolve and keep their commander out is an exploitable weakness.
Creatures like Drannith Magistrate, and commanders like Kelsien, the Plague are a huge hurdle! Not being able to cast, or keep your commander out locks a lot of Pauper EDH decks out of the game. So, having enough removal for these is a necessity!
Speaking of removal, cards like Rule of Law also need to be removed for Pauper EDH decks to play effectively! Being able to cast only one spell per turn really slows down a lot of decks, and it shuts down most Pauper EDH combo decks.
Combo is one of the strongest deck archetypes in EDH. Because combo decks can win without warning, they tend to get taken out first. Even if they're Pauper EDH decks! In spite of that, combo decks are still the most likely to win an average game of EDH. Especially if it has a combo with your commander!
Well supported draft archetypes are a decent alternative to combo. For example, Elf tribal, and sacrifice. They usually have enough cards at common for their decks to make an impact even without the commander. Since these archetypes tend to be less commander reliant, they are less likely to get locked out of the game. If your deck isn’t running a strategy like these, you will want to consider incorporating one that synergizes with it.
So in review, you’ll want everyone to discuss their decks before playing PDH Vs EDH. You’ll have to accept the fact that you’re at a disadvantage, and you’ll need a lot of removal to avoid getting locked out of the game. Finally, you’ll want to focus your deck towards a well supported strategy, so you can make an impact even without your commander.
Best of luck, and may Richard Garfield have mercy on you for your lack of rares,