They're both quite similar, and have similar attributes so it comes down to very little differences between the two. You choose if you want the Phat Humanoid with a really large tongue, or the Phat Cow standing on two legs.
Phat Humanoid (Lickilicky)
- Access to Wish and Protect
- Gets Heal Bell
- Great 110/95/95 bulk
- Solid base 85 attack, as well as access to Swords Dance and decent moves like Power Whip and Earthquake
- Slap a Choice Band on it and watch it go boom boom with Explosion
With the third biggest Wishes in the tier, only behind Alomomola and the fairly irrelevant Wigglytuff, and access to Heal Bell, Lickilicky is arguably the best cleric in NU. While Alomomola has a much higher HP stat and Regenerator, Lickilicky can take on special attackers including Kadabra, Altaria, Gardevoir without Focus Blast, Regice, and more with ease while still taking on physical hits well enough
- Crappy speed
- Gets wrecked by Fighting types
- Taunt Misdreavus laffs at everything
- SubDisable Haunter laffs as well
- Boosting Pokemon that can avoid the phasing effects of Dragon Tail and the possible paralysis of Body Slam (Eg. Substitute + Recovery Pokemon) can boost up and destroy your whole team
- Abilities are situational and kinda useless imo
Phat Cow (Miltank)
- Gets Stealth Rock
- Gets Heal Bell
- Reliable healing in Milk Drink
- Decent base 80 attack and great base 100 speed, allowing it to function as a pretty good offensive tank
- Gets Scrappy which means Ghost types can't laff at it anymore
- Sap Sipper lets her turn defensive to offensive, boosting her decent attack, and allowing her to kill stuff with her high speed
- Thick Fat lets Miltank tank Fire and Ice like a bauss
Miltank sports an excellent movepool with various support options, such as Heal Bell and Stealth Rock, which enable her to fill many different roles on your team. Her access to a reliable recovery move in Milk Drink, combined with her great HP and Defense stats, cements her position as one of the most reliable support and defensive Pokemon in the tier.
- Killed by Fighting types as well
- Powerful special attackers can break through
- Non-scrappy variants get laffed at by SubDisable Haunter
- Misdreavus laffs against everything
- Special defence is a little lacking so look at con 2 :3
So which of them is the better phat Pokemon?
Lickilicky is the better team player imo - it has Heal Bell and Wish, which allows to function by healing status and health for the team. It has better overall bulk over Miltank too.
Miltank has the ability to set up Stealth Rock, which gives space for other Pokemon to not bother doing that and just kill stuff. It's also probably a slightly better offensive Pokemon due to the higher speed. Against specific types, Fire and Ice, with Thick Fat Miltank is probably a more solid answer as well.
Both of them get walled by similar things, and killed by the same things courtesy to their typing. In the end both are great Pokemon, You choose which one.
As an NU player myself, I would probably use Miltank in Gen 5 NU just because it's a cow. And I like rocks :I