Water
Because Shellos is a water Pokemon, it is best to have at least one strong water attack in its lineup. Shellos learns Water Pulse, a basic water attack that has a chance to confuse the defending Pokemon, at level 7. It is one of the more powerful attacks to keep. Trainers also have the option of choosing an overall boost to water attacks in Rain Dance at level 22 or Muddy Water at 37, granting damage and a chance to reduce the enemy's accuracy.
Ground
Although Shellos is weak against many of the Pokemon affected by ground attacks, it is useful to keep one ground attack in the Pokemon's list of moves so that it can combat foes of varying elemental types. All Shellos start with Mud-slap, a nondamaging attack that lowers accuracy. At level 2, they gain the defensive ability Mud Sport to help repel the extra damage from electric types. Mud Bomb at level 11 is the only ground attack that does damage and has a chance to decrease accuracy, making it a viable alternative for trainers who do not wish to use Muddy Water.
Normal
The normal attacks that Shellos learn are mostly negligible, although they have use in a highly defensive strategy. Harden at level 4 raises the Pokemon's defense. Level 16 grants Hidden Power, a damaging move that is random in nature. Shellos can learn heavy damage Body Slam at level 29. Shellos does not learn Recover until level 46, so although the self-heal may be useful, it may not have room for the move by then.
TM/HM
Shellos can learn a variety of Technical Machine and Hidden Machine moves, so a trainer must consider the other Pokemon in their arsenal before selecting one to teach. Surf is always a needed HM, allowing the player to cross bodies of water. If the trainer has another Pokemon to learn Surf, any of the ice-based TM moves, such as Hail, Ice Beam or Blizzard, compliment Shellos' other abilities.