Oh, If you're talking double battles then that's another thing entirely. No use for me to start speculating your team composition, you know that better than me.
Anyway, I checked: Xurkitree with Modest nature, Perfect IVs and Full EVs in HP and Special attack. Mudsdale with Sassy nature and perfect IVs would need only 80 EVs in attack for a certain OHKO, and full EVs in HP and 80 in Sp. Def to always survive non-crit Grass Knot, which is the strongest move Xurkitree can throw it's way, exept for Grass Z-move.
That seems like very plausible stat distribution for Mudsdale, since with Stamina ability and no speed, you'll want to put your EVs in bulk and attack.
Also, we're talking about Mudsdale here. Garchomp, for example, will switch in and eat your face with no effort if you don't have Hidden Power Ice, and Dragonite, thanks to it's Multiscale ability, can take even that 4x weakness.
The tournament is singles.