Excadrill

For a long time, Excadrill was anticipated as a Ground-type attacker with real potential. And then Excadrill was released, and met those anticipations beautifully. Excadrill's power and laundry-list of resistances make it a great Pokemon in many raids, and one that tends to be surprisingly tanky against many top raid bosses that are weak to Ground thanks to its Steel sub-typing.

Max Battles

When it comes to Max Raid performance, Excadrill is very much a VIP. Its capabilities as both a Steel and Ground attacker are impressive, further bolstered by having access to two 0.5 second Fast Attacks in Metal Claw and Mud Shot. It's typing is also very valuable defensively thanks to its massive list of resistances, easily making up for its relative frailty. Additionally, it possesses a surprisingly high HP stat, which makes it a good healer with Max Spirit. Honestly, this is an outstanding Pokemon that will make Max Battles substantially easier when it's needed.

In the future, Garchomp, Groudon, and Landorus-T can outperform it offensively as a Ground attacker, while Necrozma-DM, Dialga, Gigantamax Melmetal, and Gigantamax Copperajah does the same from the Steel side. However, Excadrill's incredible Attack stat, role compression, and valuable defensive typing can keep it relevant for a long, long time.

Best PvE Offensive Moveset

• Mud Slap is preferable since Excadrill is primarily used as a Ground-type attacker.
• Mud Shot falls behind in performance due to inferior damage output. However, as it has a speedy duration of 0.5 seconds, it is the preferred Fast Attack for Max Battles to charge up the Max Meter more quickly than Mud Slap.
• Metal Claw in a nutshell performs better from a stats perspective, but isn't as useful in practice. In Max Battles, it can charge up the Max Meter quickly due to its 0.5 second duration, serving as an alternative to Mud Shot if Steel-type damage is needed.
• Scorching Sands is definitely Excadrill's best Ground Type move.
• Earthquake is stronger than Drill Run, but the later is more reliable due to being 2-bar. 
• Iron Head can pair with Metal Claw if a Steel-type attacker is needed, but Excadrill isn't the best for this role. 
• Rock Slide lacks STAB and has little use. 

Best PvE Defensive Moveset

• Mud Slap is superior to Metal Claw on defense thanks to its significantly higher base power. 
• Mud Shot has poor damage output for defense. 
• Iron Head sports the earliest damage window, and is the hardest to dodge. 
• Rock Slide doesn't get STAB, but it is hard to dodge and offers greater coverage. 
• Scorching Sands works well on Defense.
• Drill Run is a bit slower than the others, but still performs okay on defense.
• Earthquake is too slow for defense. 

Mud Slap is preferred over Mud Shot; its massive damage output is generally worth it over Mud Shot's slightly higher energy gain but far worse damage output. Metal Claw is an underwhelming move for PvP, and Steel-type coverage is typically not as valuable. 

Rock Slide ties for the least amount of energy, and provides wide coverage. Drill Run is an efficient move that is recommended over Earthquake due to significantly less energy costs. Scorching Sands is weaker than Drill Run and has a higher energy cost, making it a lesser option. However, it also has a 30% chance to debuff the target's Attack, so it's not entirely outclassed. Iron Head is typically not used due to other charge moves being more valuable.