Gragas will look to gank a lot in the early game. Try to counter this by having good vision around the map so you can spot him before he gets to a lane.
Gragas is a strong dueler and can easily take down a target if he gets the jump on them with his E. If you can dodge the E, you’ll have an easier time fighting him.
As Gragas will be ganking a lot early, his jungle will be open to the elements. If you spot him on the top side of the map, you should invade his bottom side jungle and steal away his camps.
Do not group closely together when sieging an objective or team fighting as it provides Gragas with an opportunity to knock your whole team into his with his Ultimate R.
When fighting, make sure you’re not too far forward or split from your team. If you’re too far forward, he could use his Ultimate R to push you into his team. Getting caught out like this could result in the enemy taking an objective shortly afterwards.
You can often tell Gragas is nearby when Predator kicks in. As soon as you see the marker, retreat to safety so you don’t get killed. Having deep vision around the map to spot him early will also come in handy.
Gragas can start ganking once he has access to all 3 core abilities. Keep this in mind and try to track him so you can counter gank at level 3.
Like most champions, Gragas spikes again at level 6 as his Ultimate R is a really good tool when it comes to ganking. Expect him to gank overextended lanes whenever he is level 6.
Always keep an eye on what items he’s buying. Gragas can go tank or can build a lot of AP. If he’s going AP, respect his damage output.