As a guide for those who are thinking about Water-Types, I thought I would make a list of those Pokemon that are not very capable on dry land and thus are more limited without water, usually losing mobility:
Horsea -> Seadra -> Kingdra: Can balance and hop on their tails, but are much less mobile on land.
Goldeen -> Seaking: Can use their tails to 'jump' forward, but their mobility is even less than the Horsea line.
Magikarp: Honestly, just use Gyarados as Magikarp is useless, even in the water.
Remoraid: Octillery is the goal for this Pokemon when it comes to getting out of the water.
Wailmer -> Wailord: Wailmer is small enough to bounce like a beach ball out of water, but Wailord is really a beached whale otherwise.
Feebas: Same as Magikarp, but with Milotic instead.
Luvdisc: Basically becomes a sitting duck on land.
Finneon -> Lumineon: While Lumineon's large fins can catch air like a kite, it's not a reliable means of movement.
Basculin: Even on land, it is dangerous....if one gets to close to the almost immobile Pokemon.
Alomomola: Same as Luvdisk, a sitting duck.
Tentacool -> Tentacruel: Tentacool's tentacles are not strong or numerous enough to do more than drag itself across the ground. Tentacruel, however, can move fairly well.
Chinchou -> Lanturn: Though Chinchou can hop around on land with ease, Lanturn is much more at home in the water.
Qwilfish: It can puff itself up to propel itself like Wailmer can using its strong tail as a way to bounce.
Mantyke -> Mantine: At best, they can glide, but lose mobility otherwise.
Carvanha -> Sharpedo: Though they can balance on their fins, their movement is greatly decreased.
Barboach -> Whiscash: Barboach can't move well on land, but Whiscash's strong fins allow it to move (slowly) over land much better.
Skrelp -> Dragalge: Like the Horsea line, they can balance on their tails.