Miltank

Miltank is a mini-Snorlax. Her strength lies in being a defender with few weaknesses and access to a spammable Body Slam. However, these benefits do not outweigh the fact that her stats and typing are inferior to most meta-relevant Pokemon.

One interesting parallel is that Miltank will match the performance of Snorlax when at the same CP. Thus, a powered up Miltank may be able to hold down a gym for longer. This novelty ends once you realize an egg hatch or raid catch Snorlax fits this strategy immediately out of the box.

Best PvE Offensive Moveset

• Tackle is preferable for neutral DPS, but can't be Super Effective. 

• Zen Headbutt is the worst Fast Move option available. 

• Rollout synergizes well with Ice Beam against Flying-type defenders. 

• Thunderbolt is a downgrade, but at this point maybe consider other Pokemon instead? 

• Body Slam provides good neutral STAB damage, but can't benefit from a Super Effective multiplier.

Best PvE Defensive Moveset

• Zen Headbutt is clearly superior to Tackle, offering better damage, coverage, and energy gain.

• Rollout is not primarily recommended for defense due to being resisted by Fighting-type attackers. 

• Body Slam is Miltank’s best charge move, being nearly identical to Stomp but at a lower energy cost.

• Ice Beam can give Miltank good coverage vs some attackers, with Thunderbolt performing slightly worse.  

• Gyro Ball is probably one of the worst charge moves in the game.

The addition of Rollout following the September 2022 update is what enables Miltank to see some play in PvP. It provides fast energy generation, letting Miltank access its Charge Moves sooner, but its damage output is minimal. 

Body Slam is Miltank's best Charge Move, superior to Stomp, making that mandatory. Pair that with either Ice Beam or Thunderbolt based on preference for coverage. 

The addition of a useable Fast Move (Rollout) in theory should take Miltank from zero to hero, due to its preferable Charge Moves. Body Slam gets STAB and can be spammed frequently, while Ice Beam and Thunderbolt are useful typing coverage options. Unfortunately in practice Miltank still needs further improvements to challenge the meta. The choice between Ice Beam or Thunderbolt means choosing which matchups to focus on winning, and forfeiting the others. For example, Ice Beam is necessary to defeat Venusaur and Altaria, but Thunderbolt is necessary for Alolan Marowak and various Water-type Pokemon. Miltank also does not have any utility options, nor solid answers to the various Pokemon with Fighting-type coverage in the meta such as Vigoroth, Obstagoon, and Deoxys Defense Forme. 

With Ice Beam, Miltank surprisingly has a close fight with Giratina Altered in this league if Dragon Breath is involved. Nonetheless, Greedent almost performs identically to Miltank, with a slight advantage due to having access to Crunch, which costs less energy than Miltank's coverage while also providing a chance at some utility. 

Your opponent will be milking those wins off Miltank.