Ah, the early game normal type. Normally only good for the early game, they evolve fast, and have the base stat total you'd expect. Good utility with HMs, but otherwise underwhelming. However, Gamefreak has been changing gears. Trying to make every Pokémon have a niche. And that is no where more apparent than with Greedent. Turning what would be a normally lackluster early game Pokémon into a fearsome Trick Room sweeper thanks to Belly Drum.
However, even with that design philosophy in mind, Greedent still falls short. Trick Room and Belly Drum individually are inconsistent strategies in Singles, the short timer for the former and the inherent risks of cutting your HP into half for the latter make both easy to disrupt. Putting the two strategies together? You have 3 turns to make an impact. All the setup and jumping through hoops for 3 turns of pure offense. In previous generations, this might have had merit, but with the loss of Return, Greedent's best STABs are Body Slam and Giga Impact if Dynamaxing. Luckily the Dynamax timer matches up with Greedent's ideal 3 turns of Trick Room, and Greedent's great HP makes it immensely bulky when Dynamaxed. However, getting to that point without using your Dynamax can be even more difficult. And outside of Dynamax? Giga Impact would be a death sentence while Body Slam's lack of power is all too apparent.
Greedent has some incredibly high highs, but its cripplingly poor Speed outside of Trick Room and only decent defenses with no recovery (since the Sitrus + Cheek Pouch would Ideally be used to recover from Belly Drum), vulnerability to both Status and Priority, and the work needed to get to those highs leave Greedent a gimmick. Which is still miles better than the competitive viability of Raticate, Furret and Bibarel.