Vaporeon.

Edit: Yes, Lanette. I’ll add an actual answer.

This entirely depends on what your team’s needs are, actually. Although there are a number of pokémon that function well on land, each one has entirely different capabilities. For example, if you’re looking for a pokémon that has fantastic offensive capabilities when it comes to distance attacks, slowbro is an unconventional choice but a solid one nonetheless, given its considerable power over the elements, the bulk of its species, and its ability to mega evolve. As a mega slowbro, its battle style makes it difficult to hit as well, which in combination with its natural defenses and offensive power means it can easily tear through a battle without sustaining much more than a scratch.

In terms of more conventional choices (particularly if you don’t have access to mega stones), starmie is also highly popular, made so by offensively geared trainers such as Misty. There’s a good reason for this too: starmie is an extremely fast pokémon capable of landing devastating beam-based hits, so it’s notorious for downing opponents before a trainer can utter a single order. The drawback is that starmie isn’t known at all for its defensive capabilities; in fact, its major weak point is quite literally in full display on its face. A trainer thinking about using starmie must be extremely alert at all times on the battlefield.

On the other hand, it’s difficult to take down a pokémon when it’s out of reach, which is why my final recommendation, as unconventional as it is, would be pelipper. People underestimate pelipper, I think, due to its extreme weakness to an element commonly used against water-type pokémon. However, pelipper possesses excellent defensive (aside from the obvious weakness), as well as the maneuverability to make battles rather interesting, shall we say—so long as it attacks from a distance.

If you prefer hand-to-hand combat, though, a common choice would be one of the starters (barring blastoise, of course), but perhaps the best choice would be swampert. Once mega evolved, its bulk increases, which means moves such as Waterfall or Ice Punch turn from powerful to positively devastating. Moreover, it lacks a weakness to electric-types, which adds to its tank-like capabilities. Additionally, if you already have a pelipper on your team (particularly one with the Drizzle ability), mega swampert’s powerful Waterfall makes the two of them a perfect pair.

If you’d prefer something a little less conventional, though, look towards crawdaunt. Much like pelipper, many people don’t entirely think twice about crawdaunt, but the thing is, not many of them realize crawdaunt can learn Swords Dance, a move capable of increasing the offensive power of physical moves. This is a fantastic advantage, as it provides a much needed boost to crawdaunt’s already formidable Crabhammer (among other physical techniques).

Finally, azumarill is shockingly an excellent battler in this department as well, for very similar reasons to crawdaunt: it learns Belly Drum, which drastically increases its offensive powers (albeit while hurting itself in the process). Moreover, azumarill possesses an interesting type combination that can frustrate an opponent, and its defensive capabilities and overall stamina allow it to endure a surprising amount of abuse on the field.

If you’d prefer something a bit more defensive or mixed, you really can’t get much better than toxapex for quite obvious reasons. Although it may not be the most maneuverable pokémon one could train, it is a verifiable fortress, capable of withstanding intense fire while at the same time whittling away at an opponent using its toxic moves.

Alternatively, if you’d like something that will move about a field, try either quagsire or gastrodon, both of whom are water/ground-types (that is, water-types immune to electricity) with surprisingly fantastic defensive capabilities. It’s just that gastrodon is better adapted to taking distance moves, whereas quagsire is better suited to taking physical strikes. (That and gastrodon can hold its own using distance moves itself, whereas quagsire is more geared towards trainers whose main strategy will be to frustrate their opponents with moves such as Toxic and Curse.) Alternatively, wash rotom is a pokémon few trainers would expect, but its unique typing, the durability of the washer it uses as a body, and its tendency to strike back and strike back hard make it an excellent if underrated choice.

If, meanwhile, you would prefer something with a bit more speed, greninja is infamous for it—that is, its ability to strike hard and fast and to take down an opponent before they even blink. However, that isn’t your only choice, especially if you don’t want speed for attacking. If you’re an excellent strategist, araquanid is a popular choice as well, but it’s popular for its ability to lay down traps. With the right amount of planning and perfect timing, sending an araquanid out at the beginning of the first match can potentially decide the outcome of an entire battle.

Finally, if you’re simply looking for companionship … vaporeon. It may not be the strongest pokémon on this list, but it’s certainly the friendliest.

I call bias. —LH