Smeargle can do one thing that no other Pokemon can do. Ingrain+ baton pass
Ingrain
Baton pass
Spikes
Amnesia
This moveset covers a lot of different grounds, stalling, baton passing, trapping, and special walling.
Most people would probably lead but smeargle is a fragile Pokemon. Id get some setups in before bringing him out.
My team and setup
Lead
*Ninjask
swords dance will make leech life a viable attack that will heal more especially when using substitute
Swords dance
Leech life
Substitute
Baton pass
*Scizor
Iron defense will give physical durability to the substitute while still being able to do solid damage with the swords dance pass off
Iron defense
Bullet punch
Baton pass
False swipe ( my counter to focus sashers. The ones that troll with level 1 Pokemon)
*Smeargle
Now that you have a durable substitute, plant the ingrain and start amnesia to boost the special defense. You can lay 3 layers of spikes to handle any switches.
Spikes
Amnesia
Baton pass
Ingrain
*Gliscor
Now the chain is building, let's continue and stack another trap. Also serves as a counter and sweeper to help ninjask and scissor against fire and rock types
Stealth rock
Double team
Earthquake
Baton pass
Now you have defense, special defense, attack and evasion and speed. 2 traps
You can pull your grandma Pokemon out and they can sweep the floor with your opponent.
The last 2 are purely your choice.