Well, Palossand can be good, mainly with Sandstorm in play. Shore Up is very good recovery in the sand, healing 2/3 of Palossand’s max HP. That’s a lot, if you think about it. Water Compaction is also a good ability, raising Palossand’s defense by 2 stages when hit by a water attack, allowing it to take a weak water hit, like Aqua Jet, and wall it for the rest of the time it’s in play.
Another good thing about Palossand is it’s Special Attack, and it’s main STAB moves being Shadow Ball and Earth Power. Both are good moves with a SpDef lowering chance. With Shore Up and Sandstorm set, it can make a great attacking staller, using its great defense to its advantage. The last move slot is really your choice, but I recommend Giga Drain for more healing or Amnesia for extra special bulk.
So, I do think Palossand is good in its tier (NU) with access to Shore Up, Amnesia, and Giga Drain, it can stall pretty well while hitting hard. So, I think if you like Palossand, and you kinda want to use it, then I do think Palossand is a good option in competitive.
Also, in a play through, yeah Palossand is good but you did say competitive, so I’m a bit confused.
Hope this helps! :)