I am surprised no one has posted about Trapinch yet other than you Snaquaza. Just from pure theorymon, it seems like it can become one of, if not THE BEST, Pokemon in the tier. Let's take a look at this bad boy.
HP: 45
Atk:
100
Def: 45
SpA: 45
SpD: 45
Spe:
10
Meet Dugtrio 2.0. Choice Band Trapinch is not tearing any holes in the tier any time soon, but man oh man is it "fast". Base 10 Speed makes it the fastest offensive threat in the tier,
really fast. To put it into perspective on how slow it is assuming Trapinch uses 0 Spe IV's and a Brave Nature., base 25 Pokemon
with Macho Brace will be unable to outspeed the mighty Trapinch. Only Macho Brace Escalvilier and Ferrothorn will be able to do so.
Trapinch can abuse that great speed of his to become the premier revenge killer in the tier with Arena Trap. With a positive attack nature, our Trapinch will have 69 more attack than OU's neutral-nature Dugtrio. Trapinch's power is further augmented by easy access to a Choice Band (since it is so fast) to reach a smexy 492 Attack (along with a Great-STAB EQ).
So what are Trapinch's problem? In a metagame where Pokemon can effortlessly add on bulk, Trapinch's power is less than stellar. This is further compounded by the high usage of Curse users, who gain the Speed advantage if they decide to use Macho Brace and a +1 Defense boost. Trapinch can sort of counter-act this by running a Macho Brace himself (at this point not even non-Macho Brace minimmum speed SHUCKLE can outrun you) and that most Curse users are Rock-type or Steel type. Trapinch also can not adopt any meaningful bulk himself, so you can only be used on revenge kills or risky double switches.
CB Trapper:
Trapinch (F) @ Choice Band
Trait: Arena Trap
EVs: 252 HP / 252 Atk / 4 Def (0 Spe IV)
Brave Nature (+Atk, -Spd)
- Earthquake
- Rock Slide
- Crunch
- Superpower / Quick Attack
His movepool is also pitifully small, but just precise enough to counteract some of the tiers top threats. STAB EQ is Trapinch's staple move, hitting the largest variety of targets as hard as possible as well as getting those nasty Rock-type Curse users. Rock Slide for general coverage. Crunch can be used to nail some Psychic and Ghost-types, but remember it just barely edges out over EQ in base power (150 BP STAB EQ vs 160 BP 2x Super-effective Crunch). Superpower can be used to nail other Steel-types such as Ferrothorn harder. You can also try Quick Attack for priority if you feel that your Trapinch might get outsped by certain Macho Brace Cursers, but it is pretty medicore.