Jumpluff

Jumpluff has pitiful stats for PvE, and is mostly a dex filler. Its double weakness to Ice-type attacks discourages its use for gym defense. The only niche that this cotton ball has going for it is in PvP, specifically Great League. 

Best PvE Offensive Moveset

• Bullet Seed gets STAB and allows Jumpluff to fulfill a Grass-type role.
• Infestation actually sports slightly superior stats, but lacks STAB and doesn't synergize well. 
• Fairy Wind is more beneficial for Fairy-type Pokemon. 
• Solar Beam offers the best offensive performance, dealing considerable damage. 
• Energy Ball deals more consistent damage as a 2-bar move, but falls behind overall due to how slow it is. 
• Acrobatics benefits from STAB, but lacks synergy with Jumpluff's fast moves.
• Aerial Ace is a step down and has the same problem. 
• Dazzling Gleam has no use. 

Best PvE Defensive Moveset

• Both Bullet Seed and Infestation perform almost identically on defense, the difference is miniscule. 
• Fairy Wind is one of the worst moves for defense, with its pitiful damage. 
• Aerial Ace can be used frequently as a 3-bar move, and benefits from STAB.
• Energy Ball being a Grass-type move can threaten certain Ice-type attackers that have a Water sub-typing. 
• Dazzling Gleam doesn't provide any meaningful coverage, but is faster than Energy Ball. 
• Acrobatics hits hard and fast, but takes a long time before it can be used, which is risky with Jumpluff's double weakness. 
• Solar Beam is too slow for defense. 

Fairy Wind is an interesting addition for Jumpluff; while it doesn't get STAB, the advantage of Fairy-typing helps in a handful of a matchups. Bullet Seed performs almost identically, but having STAB on a move that doesn't deal much damage isn't very significant. 

A mono Flying set of Charged Attacks featuring Acrobatics and Aerial Ace is the most common variant of Jumpluff, taking advantage of both Aerial Ace's low cost and Acrobatics's superb DPE. Energy Ball can be ran to take advantage of Jumpluff's Grass STAB, improving Jumpluff's matchup against Electric-, Rock-, and Water-type Pokemon. Dazzling Gleam can be used for extra damage against Dark- and Dragon-type opponents, but it often doesn't do much more damage than Acrobatics to be worth running. Solar Beam is too expensive, and Return doesn't have meaningful targets.