The Big Bad Wannabe is a villain who arrogantly presents themselves as a significant threat, but can't back up their claims when it comes to action or forethought, making a fool of themselves. The absolute level of menace varies widely, from an typically incompetent villain having a good day with accomplishing their goals, to a villain who could legitimately be the Big Bad, if the actual Big Bad wasn't even more skilled and competent than they are, but within the story they're in, they are (initially) presented as a big deal.

There are also many ways of revealing the villain is an over-inflated threat. A school bully might run from a real fight. In the second example, an unfair circumstance gave the villain an early victory. Sometimes it's just a matter of scale; the heroes catch a murderer, but just a copycat, not the real mastermind serial killer they were thought to be. Alternatively, the real Big Bad might prove they are worse as they outdo the wannabe, or even killing off the wannabe. Those that fall under this trope are also extremely vulnerable, both from actual Big Bads and their enemies. Sometimes they may be a beginning villain, but in other cases, it’s made clear early on (and later on) that there is a bigger threat lurking around.

Since these characters tend to be weak and easily defeated with little to no effort; it's possible for this trope can be technically considered Laughably Evil if they're played for laughs for the fact they fall below such expectations for the role of Big Bad, that they become less threatening over time or more humorous than how they present themselves due to their decisions that have led to their incompetence as capable antagonists compared to their enemies. Most of these villains tend to not be played for laughs, however.

It is important to note that Big Bag Wannabes can be legitimate threats, and be taken seriously by others in terms of a laughably evil villain, but only if they aren't presented as incompetent in the following episode(s) and are considered to be completely insignificant when compared to another, more powerful villain.

Here's the page to know more about the following trope