Hit it on the head. And Ursaring is bad. Granbull is pitiful. It has mountains of options, but it's BST and Normal-typing really let it down.
Although those are only two things, they DO weigh Granbull down to NU. If anything, it has a bit of luck to compensate with; It's speed is so poor that it works well in TR(Although Reuniclus and Conkeldurp still out-slow it) and can benefit from a huge movepool.
I'm not gonna post sets, the only ones competent have already been posted I assume.
"Mountains of options" seems to be all many Normal Type Pokemon with pitiful stats have. Look at Smeargle, Audino, and Spinda - tons of options, but all 3 are pretty "meh..." in practice. That's the boat Granbull finds itself in. Aside from a huge Attack stat and slightly-above average* HP, here's what Gran' has in stats: Nottamucho.
1. It Speed-ties Conkeldurr - a Pokemon with better everything-except-Sp.Atk (both Pokemon have negligible Special game, anyway).
2. Ursaring ties your HP
AND Defense and has better everything-else.
3. Attack is tied with 17 Pokemon and outclassed by 50 others (including all alternate forms except Arceus's). Two of the "outclass category" members aren't fully Evolved, too.
4. There are 2 Priority Moves that are Super Effective on Gran' and both can be used quite well
without STAB in most cases - Vacuum Wave and Mach Punch.
The latter is often deadlier due to STAB, decent Attack, and (possibly) Iron Fist or Technician behind it. Hitmonchan and 'top are deadly with Mach Punch (as will be DW Conk' if you feel suicidal), and Vacuum Wave Lucario and Infernape are threatening to levels Gran' wishes it could reach. You won't see many of these because of issues 1 through 3.
Your Abilities don't help much, either:
-Intimidate is very blockable (Hyper Cutter, Clear Body, White Smoke), easily reversed (Defiant and Contrary are an issue), or ignored entirely (opponent is actually a Special Attacker, has Foul Play, or Unaware Ability).
-Quick Feet makes your already-unusable Speed average under a Status Effect (which is likely going to be Burns to reduce your Attack if you're unlucky).
-Rattled has only 2 types available for use due to your Type-Immunity to Ghost. Even then, you'll need far more than Speed buffs to outrun many of your opponents.
Speaking of Foul Play, this Move is a huge advantage for Pokemon with low(or simply low
er) Attack stat and Special users. Except for Honchkrow (not advantageous to use) and Krookodile (barely advantageous to note), the Pokemon that get this Move can use Gran's superior Attack (Attack-down Nature Smeargle has incredible potential, in-particular).
With only Base 75 Defense and Base 90 HP, Gran'll be hurting from a Base 95 Power, Base 120 Attack, STAB (barring Meowth, Persian, Smeargle, Seedot, or non-Dark-Type Kecleon) Foul Play. Except for Seedot and Stall Sableye, you don't have a chance to outrun this Move without Trick Room on a buff-free encounter.
* I call 85 "average" for HP and 90 "average" for non-HP stats. I figure 70 as the base for "low" and 100 as the base for "high" with HP (85 is halfway between). Same with 80 and 100 for non-HP (90 is, again, halfway). Your numbers for finding the "average" point may vary.