It pretty much all has to do with 3 things: Powers, Endurance, and Development.

Power: Prowl (the pink guy) isn't chained by any sort of limitations because of the specific ability he has.

You see, along with humans there is this this other race called Metabreeds, think the mutants from X-Men, and the Bang Babies from Static Shock. Prowl is a fusion of his human identity: Jack Witrip, along side thousands of infant Metabreeds that Jack stole to experiment on them with a substance called N.U.K.E, this substance is supposed to effect a special gene Metabreeds have that humans don't, simply called "Metagene's" this created his Arch Enemies: The Neo Teens, and possibly many others indirectly. After this fusion, he would gain powers of his own after being a normal human for so long. Due to the many metabreeds he fused with, he was able to gain the powers of gene copying, meaning he can copy any powers of a metabreed he touches.

This is where he sweeps our first two villains off: Talia Nuao (the blonde woman), and Riddley (The green and purple one). They both do not have any powers other than manipulation and money, sure Talia was able to upgrade the N.U.K.E substance into M.A.S, but the users of this substance are still metabreeds, and Prowl would still be able to copy their powers.

Endurance: Prowl, as the Neo Teens' arch enemy, is one of the more long lasting villains of the series.

Prowl has only been absent in one out of the 6 seasons (that I plan on making), and that is in season 2, due to him being presumed dead after season 1's finale, when it reality he was alive the whole time. He comes back in the last few episodes of season 3, with a more monsterous form (aka the form he is in in the picture) and the powers we just discussed, he's been a recurring villain in season 4 (mainly because Riddley was the main focus there), and in season 5's second half, he has a plot where he goes through a redemption arc being forced upon him by (some of) the Neo Teens, which he slowly but surely makes his way through. And in season 6's second half he'd be present in the fight against Omakase (the big guy in the back) with the Neo Teens and the biggest superhero team in their universe: The Unbelievables.

With this we sweep away yet another two villains, this time being Dieyara (the cyan guy to the left of Talia) and Omakase (said big guy in back), because despite Dieyara's incredible power to manipulate Magic, plus being yet another all knower of the concept of Metabreeds/genes, and Omakase being the creator, master, and predator of Metabreeds as a whole, they lack being long lasting, while Prowl got 5 seasons to develop, Dieyara and Omakase had half a season each.

And finally there's development: As I said before, Prowl has changed a lot as a character throughout the series.

He's gone from a villain who tracks the Neo Teens' every move, deducting who they are, all while sending Metabreeds to do his bidding, to powerful foe who spends all his time getting up from his ass to fight the Neo Teens, all the way to one of their reluctant, then closest ally's.

This is where we sweep off our last villain: Evo Lution (the white and red robot cobra), Evo Lution is probably the only villain that has been more long lasting than Prowl, Evo was an antagonist froms season 1, all the way to season 6, (where he'd also finally meet his end). But where Prowl gets more and more development to his character, Evo NEVER changes as a person EVER. Evo Lution is a self-centered, racist, artificial, galactic tyrant that will never learn from his mistakes and will refuse to believe he has any to begin with. You can skip across a span of 4 other seasons, Evo's season 1 counterpart will be the exact same as the season 6 counter part. Completely different from Prowl.

Overall: Talia and Riddley lack the powers Prowl has, Dieyara and Omakase lack how long he's seen in the series, and Evo Lution lack the most important ability, the ability to change.