Seismitoad

Seismitoad looks like a bulky toad that doesn't mess around, however its unimpressive ATK stat offers little in the presence of powerful Pokemon like Kyogre and Groudon. 

Best PvE Offensive Moveset

• Bubble tends to perform best when attacking a neutral opponent. 
• Mud Shot has better synergy with Seismitoad's strongest charge move, but can fall behind without a typing advantage.
• Earth Power with STAB offers the highest amount of damage output. 
• Sludge Bomb doesn't have any utility, nor does it synergize with other moves. 
• Muddy Water gets STAB and has typing synergy, but its base power is so bad it's not worth considering. 

Best PvE Defensive Moveset

• Bubble hits harder on defense, and is generally the better choice. 
• Mud Shot has poor damage output defensively. 
• Earth Power deals good damage on defense, but is very easy to dodge. 
• Sludge Bomb is the most difficult to dodge, and can cover Seismitoad's weakness to Grass-types. 
• Muddy Water as a 3-bar move can be used frequently, but is not very threatening. 

Bubble features considerably more damage output than Mud Shot, however the latter generates energy faster. Either option can work depending on how you want to use Seismitoad. 

Earth Power is Seismitoad's strongest charge move, and provides wide coverage against common meta Pokemon. Muddy Water has pitiful damage output, but costs much less energy and is used primarily to bait shields and/or debuff opponents. Sludge Bomb can be elected for coverage against Seismitoad's weakness to Grass-type Pokemon, and can also hit Flying-types for some decent damage.