>>418076861. Nidoking and Nidoqueen are definetely the first choices. Speedrunners prove it (a lot).
2. Ampharos is also the choice for Gen2, the first two gym battles are a breeze with Mareep/Flaaffy and Ampharos evolving early doens't help. You can argue Gastly (no one carries anything remotely strong against it in throgh all the game besides Psychic-types) and Wooper/Quagsire, but I don't see them as exploitable.
3. Hariyama. Its bulk and stats reachable before the third gym simply broke the game's difficulty. That shit doesn't die. This would be more accurate if it wasn't boring as fuck to train Gardevoir, even though it fits the written concept of Bruiser, is not as easy to obtain as Hariyama. Breloom could also be mentioned, but also not as exploitable as Hariyama.
4. Both Staraptor and Luxray (with Intimidate) are Bruisers and that's why everyone and their moms use those in every single Pokémon team. Roserade is a close third place. The fact the rest of the dex is not even remotely as good makes the rest of DPP's dex feel like dumbster trash.
5. Stoutland and Excadrill are good examples, but for this one I can say none of them really fits the Bruiser concept as they're not even as unbalanced as the other mentioned until now are. The expanded dex and the presence of many many options (you liking their designs or not) made those games harder to speedrun.
6. Aegislash and that's it, by far. The moment Honedge appears everyone is still in the start of the learning set, carrying many unnafected Normal-type attacks. The moment you have Doublade, Eviolite won't. let. it. die. Never. And Aegislash is exploitable as fuck, the AI can barely touch it. Not fun 0/10.
7. This one fits a little in Gen 5 context. The closest thing to it is Magnemite, which destroys everything in the start of the game, while Magneton/Magnezone outspeeds everything (the dex is 2 slow) and endures hits from almost every Totem (except maybe Wishiwashi, Marowak and Salazzle and Kommo-o).