Butterfree

Type Tier
Bug / Flying UU
Statistics
Stat
HP
60
323
Atk
45
188
Def
50
198
SpA
80
258
SpD
80
258
Spe
70
238
Name Item

Double Powder Butterfree

Leftovers
Moveset
~ Sleep Powder
~ Stun Spore
~ Psychic / Nightmare
~ Giga Drain

Go, useless butterfly! Bad typing + bad stats + bad move pool = bad Pokémon. OK, this may be one of the few times you'll see Nightmare as a move option. Sleep Powder and Stun Spore are needed. Psychic and Giga Drain are there because Butterfree really doesn't learn anything more useful, nor can it do too much more. Nightmare the Sleep Talkers, though it's doubtful you will live long enough for it to matter.

Other Options

That's really about it. Reflect and Safeguard can benefit your team. Never EVER use Whirlwind unless you're crazy, as Butterfree can't Whirlwind well at all since it is ridiculously fragile. Toxic because what else will it use... String Shot?

Opinion

Butterfree stinks. Really, it does. If it had a special typing, that still wouldn't make it any more useful. It gets the ability to induce Sleep and an additional status, which is nice—too bad it can't effectively force switches like say, Jumpluff. It's hard to think of a situation where Butterfree could be useful.

Counters

Pokémon beats Butterfree with move. Seriously, Butterfree dies to practically everything, and it can't do much else to them but sleep / paralyze them. And with Heal Bell and Sleep Talkers abound, it sort of nullifies Double Powder's effectiveness.

Zapdos willingly takes the sleep and hits back with STAB Thunderbolt and Drill Peck. Arcanine is much the same with Fire Blast. Heal Bellers can nullify any of Butterfree's effectiveness, and any strong STAB or super effective attack sends Butterfree running.