Goodra

Goodra is arguably the happiest Pseudo-Legendary Pokemon in the whole of the series. It has a nearly ever-present smile, and is just a bouncy tub of jelly. However, happiness and viability are not the same thing. As a raider, Goodra is vastly outclassed due to its staggeringly powerful competition and less than ideal moveset. It can be a solid defender thanks to its stats and diverse move options, but that's about the only niche that it can fill in the current meta.

Best PvE Offensive Moveset

• Dragon Breath and Draco Meteor work together to give Goodra its best moveset potential
• Water Gun and Aqua Tail can be used together, but they really don't do much damage, even when 4x effective.
• Sludge Wave, Muddy Water, Thunder Punch*, and Power Whip fall short.

Best PvE Defensive Moveset

• Dragon Breath is slightly better than Water Gun, though they're both viable choices for defense.
• Muddy Water and Aqua Tail are effectively the same move on Defense. They seem like the best options for their low energy cost, but they're also very weak.
• Thunder Punch* is outstanding on paper, but it's resisted by most of its its would-be Dragon counters, as well as double-resisted by Mamoswine/Shadow Mamoswine, one of the most common Ice Type attackers. It's still good, though.
• Power Whip has some coverage issues, but it's strong and has a reasonable energy cost
• Sludge Wave offers counter-coverage against Fairy Types, but it's also very expensive to use.
• Draco Meteor has high power and great neutral coverage, but it's also very expensive and easy to dodge. 

Both of Goodra's fast moves provide decent energy generation and are very easy to use thanks to their fast animations. Dragon Breath is the stronger choice, benefiting from STAB and also being stronger stat-wise. 

Aqua Tail is a spammy coverage option that helps it threaten Steel-type Pokemon. Power Whip is a strong Grass-type charge move that costs a moderate amount of energy, and provides useful coverage against common Water-types. Draco Meteor is powerful with STAB, and though it debuffs the user harshly, the threat of its massive damage is not to be underestimated. However choosing this move gives up other coverage options. Thunder Punch* is pretty spammable, and can keep Goodra's matchup against most opposing Water Types strong, but it's generally a bit less useful in many scenarios. Sludge Wave isn't as powerful and lacks STAB, but it can be a nasty surprise to Fairy-type Pokemon.