Pokémon UNITE features all kinds of different characters that contribute necessary abilities that help a team flourish. These Pokémon can all be sorted into categories such as Attackers, All-Rounders, Supporters, Speedsters, and of course, Defenders.
Defenders do best when they play in the front line, block enemies from coming near the goal zone, and pair up with an attacker. Defenders often have really good health sustain in fights and can survive in most situations if they play safely. All this being said, some UNITE Defenders are much better than others.
Slowbro
Slowbro is sadly not one of the strongest water-type Pokémon, but he is a versatile Defender that can build himself up with different held items and abilities to aid with whatever team composition he's given. Though he doesn't have as much health or durability as other Defenders like Snorlax or Blastoise, he has good range and great Supporter skills to aid Attackers.
It is important to note that Slowbro is an intermediately difficult character. He doesn't have a ton of moves that will help him get around when he needs to escape, but this can be easily remedied with Eject Button equipped. Overall, Slowbro is one of the weakest Defenders because he just isn't tanky enough to survive. His UNITE move is useful as a total immobilization, but because it takes a while to come off cool down, he can't depend on it to save him.
Mamoswine
Mamoswine is a Defender that has many great crowd control moves and can start fights with his Horsepower ability. Though he isn't seen all that often in games, he is valuable in team fights and can make it impossible for enemies to play the game. Mamoswine is also a great lane character and does better when paired with a damage heavy Attacker.
Mamoswine, however, is also a character with intermediate difficultly that doesn't scale all that well into the late game. Though he's quite tanky and can be important during the midgame, he is not that useful early on in the match which can make playing him not entirely worth his difficulty level.
Greedent
Greedent debuted this past Halloween in a festival event on Pokémon UNITE. He is also a great Supporter or Defender. Since Greedent creates berries that restore the health of any character that consumes them, the Pokémon is able to give health back to his teammates while doing immense damage to adversaries.
The only problem with Greedent is that he's extremely challenging to play and requires really good aiming skills to actually hit his abilities. Also, unlike other Defenders, Greedent doesn't already have his high health stored, he must rely on his berries to restore himself. Because of this, Greedent leans a little too heavily on trying to collect berries rather than actually playing the game. He is a durable character that just takes practice to be able to play him well.
Blastoise
Blastoise, who is in one of the best battles of the Pokémon anime, is a ranged Defender that can take a ton of damage and crowd control enemies when needed. His gap-closing abilities make it easy for him to chase down enemy Pokémon, while his health sustain assures that he can outlast most other characters. Blastoise is challenging for Attackers to face alone because he has incredible sustain and can chase enemies.
With this in mind, Blastoise has some of the longest cooldown times on his moves in the entire game, and his UNITE move has a slow startup. His Rapid-Spin ability is also a little uncomfortable to use because its effects are delayed somewhat. Blastoise, even with these problems, is one of the strongest Defender Pokémon in the game.
Crustle
Crustle is one of the original Defenders and has many abilities that can be used to trap or limit an enemy's mobility. While he lacks tons of damage, his larger health bar helps with his survival.
Because Crustle is more focused on isolation and how he places his abilities, he can be harder for people to pick up, especially if he is played on an iPhone rather than a Nintendo Switch. Crustle, if played well, can also carry teams with his Defending moves and make it impossible for enemy Pokémon to score on his side of the map.
Snorlax
Snorlax, one of the strongest normal-type Pokémon, is basically just a meat shield that can soak in a ton of damage while his attacker teammates do all the heavy lifting. Not only is he relatively simple to play, but he can also be a lot of fun, as he just absorbs all of the damage in team fights while staying alive and stunning enemies.
Snorlax's only downside is that he has a pretty weak early and late game. He doesn't scale all that much and he is the most useful in mid-game fights over Dreadnaw or Rotom. He also lanes really well with Pikachu or other characters that do long-ranged damage. Snorlax is not only one of the most useful Defenders, but he also is a great choice for any beginner who just wants to have fun in a game without constantly dying.