The purpose of this set is to take advantage of Simple to receive +2 Attack and Defense from a single Curse. Return is the main STAB move on the set. Aqua Tail is used for coverage, only missing out on Frillish, Lileep, and Ferroseed. Unfortunately, due to Simple, Curse reduces Bidoof's Speed by two stages. Bidoof has access to STAB Quick Attack, though, mitigating the Speed drops somewhat.
The given EVs maximize Bidoof's HP, so when combined with Eviolite, it will be able to take hits. The rest maximize Attack and give it a boost in Defense, allowing it to reach an impressive 28 Attack and 22 Defense after a single Curse. This set appreciates entry hazard support, as it wears down the opponent's team and makes it significantly easier to acquire boosts. Likewise, because of the popularity of Fighting-type Pokemon, it is recommended to run dual screen support. That way, Bidoof will have a much easier time setting up.
Unfortunately, it is rather hard to set up with Curse when Pokemon such as Mienfoo, Riolu, Croagunk, and Timburr are so common. These Pokemon threaten Bidoof with their super effective STAB attacks, forcing it out before it can boost. Likewise, Ferroseed, Frillish, and Lileep are able to take on this set, as they resist or are immune to every move it carries. Accordingly, this set appreciates partners that are able to take care of these Pokemon. Mixed Houndour, for example, is able to OHKO Ferroseed with Fire Blast and 2HKO Frillish with Crunch. Special Snover, with Blizzard, Giga Drain, and Hidden Power Fire, is also able to take out these Pokemon. Fighting-type Pokemon such as Mienfoo and Croagunk make good partners as well, as they can check Ferroseed, Lileep, and opposing Fighting-type Pokemon that give Bidoof a difficult time. Choice Scarf Flying-type Pokemon such as Taillow threaten Fighting-type Pokemon with Brave Bird. Gastly and Abra make good partners for the same reason. Gastly can also take care of Slowpoke, which doesn't take much from this set due to its high Defense. Special attackers that are immune to or resist Quick Attack, such as Gastly and Drifloon, also give this set problems, as they can outspeed and kill Bidoof. Partners, such as Stunky, that can take care of Ghost-type Pokemon are helpful to deal with these threats.