Pokemon with the Crush specialty are the shortcut for Green Paint. Manual gathering works too, but a dedicated helper means you're never caught short. It goes into 4 recipes, so having a passive supply helps.

Paint used to color items green

Raw Material
Lum BerryCrushCrushGreen Paint
ShopSmearguru / Palette Town Shop
Bleak Beach (Smearguru hut), Palette Town (Level 5)
GravelerCrushAmauraCrushRampardosCrushBastiodonCrushAurorusCrushSteelixCrushElectivireCrushShieldonCrush

Green Paint goes into Paint Balloon Aquamarine, Paint Balloon Brown and 2 more. Most fall under Other — use the filters below to narrow it down.

4 recipes
Paint Balloon AquamarineOther
Green Paintx1Cyan Paintx1›
Paint Balloon BrownOther
Red Paintx1›Green Paintx1
Paint Balloon GreenOther
Green Paintx2
Paint Balloon LimeOther
Green Paintx1Yellow Paintx1›