Lets start with the fast mana cards and see if theres anything that could potentially come off the banned list
A 3/3 for four mana that provides all other Pirates with +1/+1, Admiral Beckett Brass states that during its controller's end step, its controller can gain control of any nonland permanent controlled by a player that was dealt combat damage by three or more pirates
Arasta of the Endless Web Next up we have Arasta of the Endless Web, a spider commander who produces a 1/2 with reach whenever an opponent casts an instant or sorcery
However, say you have a creature, artifact, enchantment, and land card in your graveyard, you'll be able to search for any land or creature card instead
If it starts swinging and dealing out combat damage, people will get dead fast
That said, there are plenty of cards under the five-dollar threshold that are great for playing in other formats or that have a lot of utility in decks, even if theyre not the main focus