rflower

With three colours, I would suggest some fetchlands I think there are three options for Pauper: Evolving Wilds, Terramorphic Expanse and Ash Barrens. Dual colour life-tap lands and bounce lands could also be of use.

I empathize with the budget theme. An obvious upgrade from the guildgates is Swiftwater Cliffs. Also, Baral is only 2-3 dollars and he is the reason why storm decks are being played again so I would consider the cost for a least a few.
Also what about Empty the Warrens?

Sorry it just annoying that you could go down one of the extra cards for the last Marshal and there seems no reason not to...

Mogg War Marshall is better because you can sacrifice it for no creature loss. You can also chump block the turn it comes in and if you have nothing else to do pay its echo cost to give it a second life. It also triggers Foundry Street Denizen one extra time. The downside is the summoning sickness on the second token.

I do not understand. Do you agree that Mogg War Marshall is better than Dragon Fodder or Krenko's Command?

oh true, good point

But wouldn't it be better to take out a Dragon Fodder or Krenko's Command for the fourth Mogg War Marshal?

Why not four Mogg War Marshall?

But if you have two copters?

I did forget Dryad Arbor. It's a high risk - high reward play early in the game though and late game, when you don't mind losing a land to removal, you would might rather a more impactful spell anyway. I see your point though.
I don't have much experience with Dryad Arbor. Is it often blow up by opponent's removal. In the first game you they would have hand full of dead removal but in the next maybe they would board it out. Even Dryad Arbor makes them keep it in its a win for you. On the whole I like the synergy between the two but since you only have one Arbor maybe you should go down a Copter.

I disagree that Smuggler's Copter is a good card here. The only card worth crewing it is Sram himself and you only have two of him. The hexproof creatures would much rather just be enchanted, same goes for Kor Spiritdancer

Isn't Mogg War Marshall always better than Dragon Fodder or Krenko's Command? Also what about Dynacharge?

Holy Mantle plus Palace Guard is nice and cute.

Cloudblazer, more deadeye harpooners, Fogwalk. I would creatures such as these that actually synergise with bouncing as opposed to creatures with no abilities. I would also go down to 60 cards and add some fetch lands.

Multiple Pia's Revolutions on the battlefield at once should trigger separately..?

Electrickery over Scouring Sands

Mutagenic Growth?

Lost Legacy only draws you cards for each card you lost from your hand. It won't help Fateful Showdown at all.. Gravepurge will make you wait ages to draw some cards that you don't even want.
Sorry, it is an interesting idea but think about what you're doing and how inefficient it is: there is no real combo.

Can I please explain the combo? I don't see the use of Lost Legacy..

Eldritch Evolution, Genesis Hydra, Chord of Calling