I have been playing LoL for awhile now and I have noticed something, Alistar is kind of under powered, while he has excellent champion control i.e his push back and his knock up. And has fairly good AP/Damage ratios. It's not enough to help him stand on his own, his niche is filled better by Cho'Gath. I am essentially asking that he be reworked simillar to how Ryze and Heimerdinger have been. I have suggestions.
Collossal Strength: is fine
Pulverize: Considering some other champs have similar abilities i.e Cho'Gath the cool down time is a tad long considering it doesnt add the slow or even have the range of Cho'Gath's, and has lower base damage. My suggestion is a lower cooldown 10 or 9 seconds, as opposed to the current 15. and it should scale with bonus AD instead of AP as it would synergize with his ult beter.
Headbutt: This move has good cooldown and damage, but once again I'd recommend bonus AD scaling and possibly lower base damage instead to better synergize with his ult.
Triumphant Roar: is fine
Unbreakable Will: I think it would be much more useful if the suggestions above were put into affect. Other than that is fine.
I think by making these changes you would have Alistar in a better situation to be more unique, aswell as just working better over all. And would give him his own niche as an AD tank.