He's a big guy for sure. But I'd say that's actually his weakness. 5* means the other cards in the deck might not be the best cards. In other words, beat him by defeating most everyone else.

For example: I bluff my Sunder or other decent 3*, they usually play they're Ghumbo with a decent amount of pillz. I'm ready with my other cards to take the game. But I use nukes like Jay, so that may not be one of the best examples.

Anyone else have their way to beat that beast of a Swamp Man?

Many cards can take down Ghumbo.

Danae.
Dagg.
Deea
Marina (potential to win or remove 3 damage).
Wolfgang (same as above)
Dawn (same as above)
Rolph
Askai
Mindy
Selma (her +1 pill acts as a +14 attack if you overpil and win)
Smokey Cr (even more attack potential than Selma)
Kristin
Vengeful Chiara
Caelus
Corvus
Mono Scubb
Mono Sandro
Mono Sasha
Mono Taljion
Mono John
Mono Oscar
Confident Katja
Copper

And so on...

Lol Ghumbo isn't even that bad. Any card can defeat any card.

I would count Archibald and Bryan. that's the only reason why i use 3 La Junta cards with my Eklore + Roots cards

Danae. - ja
Dagg. - ja
Deea - uh not really ?
Marina (potential to win or remove 3 damage). - you forget the sob of Ghumbo, so dont
Wolfgang (same as above) - dont
Dwan (same as above) - yeah, have you ever seen her in elo ?
Rolph - yeah up to 4 pills
Askai - yeah see is just sexy
Mindy - ja
Selma (her +1 pill acts as a +14 attack if you overpil and win) - ja but what if Ghumbo geusses right ? and gets 1 more pill ? you get pill disadantage and massive life disadvantage
Smokey Cr (even more attack potential than Selma) - again not really, you will just get more pills back IF you win
Kristin - ja
Vengeful Chiara - ja chiara is beast
Caelus - ja
Corvus - just as smokey - as Selma it is tricky
Mono Scubb - well this one is very tricky with low power but he can be a good bluff to but so can Ghumbo
Mono Sandro - yeah
Mono Sasha - yeah
Mono Taljion - yeah if both use 1 pill then its an equal fight and Taljion will win but over 1 pill on Ghumbo and he loses pill for pill
Mono John - jup
Mono Oscar - jup
Confident Katja -jup
Copper - jup

so some are quite tricky and this is equal pill battles, and Ghumbo is mostley easy to play around his counters, except for if the oppenent has 2 or more effective counters.when it is 2 you might still get him through if you want to, depending on who starts the game.also Ghumbo can be bluffed to ! i dont think by any means that Ghumbo should be banned, he is very good but yeah, most of not every clan have there big boys.

A ton of cards can take him down. And even when you don't, he's a Hefty 5 stars, meaning the other cards are bad. Another thing I notice:
If Ghumbo is played, they don't pill big knowing people will bluff. So, using a good amount of pillz, he's beatable.