How can you beat wondertomb?

Answer 1

If you bring in weather effects (hail or sandstorm), then that will damage it. Also, burns or poison will damage it.

OR

Simply use Miltank + Scrappy + Brick Break + Choice Band = 2/3HKO. Spiritomb can't do sh*t to Miltank with Shadow Sneak or anything else.

OR

Focus Sash/Choice Band + Mold Breaking Rampardos/Pinsir, Spiritomb can't do anything except be sashed (where Sandstorm comes in).

OR

Jirachi Doom Desire + Skarmbliss Wish combo on it if it has a Wondertomb party.

OR

Breloom comes in and maximize Spore usage (since the opponent uses Wondertomb, technically no clause is in effect as if he can cheat, you can too). After, a Pokemon that can hit it comes in and pwns it.

OR

Use a fighting Pokemon like Machamp + No Guard, use Foresight and kill it with a super effective Dynamic Punch.

OR

Use a Pokemon with Fire Fang; like Entei.

OR

Use your own Wondertomb, what can he do?

OR

Use Gastro Acid or Worry Seed, and go in for the kill.

OR

Go up to the challenger and kick his balls and take a dump all over his DS.

NOTES:

1. Set Stealth Rock.

2. Set Sandstorm (with TTar if preferred since it has Fire Fang)