Pygmy puffers (Carinotetraodon travancoricus) are also known a dwarf puffers, pea puffers and malabar puffers, this search will tell you everything you need to know.
Each Dwarf Puffer requires 5 gallons of water, this is because even though they only grow up to 1", they are territorial and messy eaters. So good filteration is also required.
For the tank decoration, it is completely up to your own personal choice. However, here are some things which they are thought to like: They like a sand substrate (like all puffers they like to dig slightly) and they also prefer heavily planted tank with bogwood and rocks. Bright light is also preferred.
Bristlenose Plecos hae been reputed to work as a cleanup crw, but are known as poop machines themselves, so you will still need decent filteration.