I personally prefer the grass immunity granted by Sap sipper brings but Gooey can be great for bogging down those annoying physical sweepers.
You could go for a Specially defensive wall with assault vest, and drop your EV's in special attack, HP and the rest into defence and a Modest nature, with this distribution you can wall specials, sponge up a physical hit thanks to the HP bulk and gooey punishes them, then retaliate with the offensive move of your choice, combining Goodra's naturally high special attack stat and more likely then not a super effective hit resulting in a KO.
Ice Beam
Thunderbolt
flamethrower
Dragon Pulse
You could also take the invested HP and throw it in defence or even lower your special attack though that'll cut into your ability to KO a fair bit.