Jumpluff
Chlorophyll
Speed doubles in sun.
Type Tier
Grass / Flying BL
Statistics
Min- Min Max Max+
HP
75
 - 291 354 -
Atk
55
 131 146 209 229
Def
70
 158 176 239 262
SpA
55
 131 146 209 229
SpD
85
 185 206 269 295
Spe
110
 230 256 319 350
Name Item Nature

Subseeder

 Leftovers Jolly
Moveset EVs
~ Encore
~ Leech Seed
~ Substitute
~ Sleep Powder
188 HP / 104 SpD / 216 Spe

Annoying Jumpluff, almost useless without Spikes. Sleep Powder a foe, and Leech Seed / Substitute over and over until they die or switch out again. Encore can be used to keep foes like Snorlax Cursing and Metagross Earthquaking. The main problem with this set is that Substitute and Leech Seed have 16 PP max, which can run out faster than you'd think.

Name Item Nature

Sleepseeder + offensive move

 Leftovers Jolly
Moveset EVs
~ Hidden Power Flying
~ Swords Dance / Substitute
~ Leech Seed
~ Sleep Powder
148 HP / 140 Atk / 220 Spe

Same premise as the first, however you have some sort of way to hurt Grass types who are immune to Leech Seed.

Other Options

Stun Spore can help scout for full paralysis behind a Substitute, giving you some free turns. Reflect can make Jumpluff's Substitutes unbreakable in one hit by most physical moves not called Rock Slide and Hidden Power Flying. Jumpluff can use Toxic to really pile on the ancillary damage combined with Leech Seed.

EVs

You'll want at least 340 Speed to beat Adamant Dugtrio and slower. The rest should go in HP and defenses. If using Swords Dance or Hidden Power Flying, you'll want 181 Attack (140 EVs) to OHKO Heracross and 2HKO Medicham.

Opinion

A bad Sceptile. However, it has potential to force a lot of switches with Leech Seed and Encore. It is pretty useful if your team happens to have a Spiker along.

Counters

Other Grass Pokémon, Hidden Power Ice Jolteon / Raikou, Alakazam, Aerodactyl. Tyranitar's Sand Stream can help prevent it from recovering as much HP, but it will also let its Leech Seed be that much more effective.