Ah, Techniloom, one of the most difficult threats to switch into due to the threat of Spore. For that reason, it's pretty difficult to counter Breloom with just one Pokemon since you need sleep fodder to get your counter in safely, but after that Breloom is fairly easy to counter with this Pokemon:
Latias (F) @ Leftovers
Trait: Levitate
EVs: 108 HP / 148 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Draco Meteor
- Surf
- Psyshock
- Recover
Before I go any further, it goes without saying that this Latias prefers to operate in rain due to the power boost in Surf. This allows her to go without having to use Draco Meteor on many occasions. Anyway, onto the moveset and what it does. Draco Meteor still hits really hard despite not having anything to boost it. Very useful for when you need to get rid of an opposing Dragon type on the double. Surf gets pseudo-STAB in rain and allows Latias to take on the likes of Heatran, Physically Defensive Skarmory, Forretress, and Magnezone lacking Specs HP Ice among many other threats. Psyshock is what makes this set so devestating to virtually every Fighting type in the tier. Techniloom is unable to get by Latias with an unboosted Stone Edge, and as long as you have something put to sleep by Spore, Latias can come in time and again while Recovering off the damage. However, Psyshock's use isn't just for Breloom. Two other very popular and destructive Fighting types, Terrakion and Keldeo, also get put in their place by Psyshock with a little bit of residual damage. Also, many rain teams are unable to spam their powerful Water moves if the opponent still has a Toxicroak or Virizion waiting in the wings. This Latias is perfect for taking down both (watch out for Sucker Punch on Toxicroak) It's also useful for getting rid of Tentacruel and detering it from coming in to spin your hazards away or set up its own Toxic Spikes. Now that I've gone into detail about Psyshock enough, the last move is Recover which allows Latias to keep chasing these threats around.
A Timid nature is used along with max Speed EVs in order to get the jump on CM Keldeo and non-Scarf Terrakion. After that, 148 Special Attack EVs are necessary to ensure the KOs of Keldeo and Terrakion with Psyshock after they switch into SR and 2 layers of Spikes. The rest of the EVs are thrown into HP to augment Latias's natural bulk which is her main advantage over her more aggressive brother, Latios. Obviously, this set is helpless against Ferrothorn as it resists every move on the set so a Techniloom of your own can actually be very helpful among other Fighting types such as Keldeo and Terrakion. As said in the opening, this Latias loves rain, but it's best used on a rain team that can supply it with entry hazard support. Ferrothorn is a great partner in this regard for its ability to setup SR and Spikes. Landorus-T is also a solid partner for its ability to setup SR. It's Intimidate ability is able to relieve the strain on Latias to switch into strong physical attackers such as Breloom and Terrakion. It also keeps Scizor and Tyranitar (be careful of Ice Beam) in check, two very big threats to Latias.
In short, this Latias is a great addition to any rain team needing a strong defensive pivot that can tank hits, get rid of most Fighting types, and sweep on her own if need be.
Techniloom calcs vs. this Latias:
252 +2 Attack Life Orb Techniloom Mach Punch vs. 108 HP / 0 Def Latias: 46.65% - 54.88% (2-3HKO; guaranteed 2HKO with SR))
252 +2 Attack Life Orb Techniloom Stone Edge vs. 108 HP / 0 Def Latias: 103.68% - 121.95% (OHKO)
252 Atk Choice Band Techniloom Stone Edge vs. 108 HP / 0 Def Latias: 59.76% - 70.43% (guaranteed 2HKO)
Basically, unless Techniloom is boosted to +2 and predicts the Latias switch-in with Stone Edge, then Latias is a pretty safe bet once you've given up something as sleep fodder. Otherwise, Latias wins in virtually all situations against Techniloom as long as you've kept her in good health.