When Update 3.1 to Update 3.7 were released, they sent ripples through the WR playerbase. Many players thought (and still do) that many of the new robots and weapons to be overpowered. Even worse, they costed components, a new expensive form of currency that cost even more than components. This meant that these new robots and weapons were largely unavailable to the majority of players except those who decided to spend large amounts of money, frustrating many.
Firstly, we have the infamous Shocktrain. This weapon rapidly acquired a notorious reputation for being overpowered in almost every way. It was the best mid-range weapon, with a range of 500m, a reload of 5 seconds and it dealt the same damage as the Trebuchet. Even worse, it had a chain effect: damage would be also dealt to the nearest 2-3 robots close to the target, albeit the damage was reduced.
This chain effect discouraged one of the core foundation of WR strategy: Teamwork. Groups of brawlers such as Lancelot and Leos, previously a common sight on the battlefield and a cause for huge and fierce battles now split up more often, fearing one or two shocktrain builds that could rapidly decimate their ranks. This allowed other robots to then pick them off one by one, it was almost a matter of which team had spent the most money that decided the battle before it even started, not by skill or tactics.
The Shocktrain Bulgasari was feared in particular, as it could use its Dash ability to avoid retaliation and its physical shield to absorb the damage received. Then Pixonic finally reacted. In Update 3.7 they increased the reload time of the Shocktrain from 5 to 7 seconds. Whilst this was helpful, it was only a slight nerf and Shocktrain users were largely unaffected. Until its damage is reduced substantially, the Shocktrain will remain an overpowered weapon.
Secondly we have the Bulgasari. With the Dash ability, the most durable physical shield in the game, high health and firepower, this robot was quite literally a game-changer. The meta evolved from Lancelots to Bulgasaris, often equipped with Tarans, Orkans and the Shocktrain. Its health (over 190,000) was enough to rival a heavy robot, having more health than the Rhino and Lancelot. In addition to this, it also has the most durable physical shield in the game on its side. These two formidable characteristics rapidly made it into the workhorse of the higher leagues. Although it is true that the shield doesn't block splash damage, the Bulgasaris Dash ability allows it to escape or avoid confrontations it can't win and hide behind cover, as well as providing a speed boost.
The Bulgasari also has very high firepower for a medium robot. This, coupled with its durability and the Dash ability allows it to use hit and run tactics to devastating effect, especially when equipped with Orkans and Shocktrains. Its armour allows it to use sustained damage weapons such as the Taran and Scourge, and its pilots often turn to the side when reloading to block enemy fire with the shield. In short, the Bulgasari has enough firepower to rapidly destroy all its medium counterparts. Heavily armoured medium robots such as the Boa, despite having more health than the Bulgasari, simply cannot compete due to the physical shield and higher firepower, as well as the Dash ability.
Even the best heavy robots such as the Lancelot, or extremely durable robots such as the Raijin (which has shields and a firepower boost) sometimes cannot effectively counter the Bulgasari. The high firepower potential of the Bulgasari's 3 medium weapon slots allows it to unleash devastating barrages onto its heavy opponents, then dash out of danger before retaliation. The large frame of heavy robots also means that they are almost impossible to miss. Anciles are also of limited use, as the Bulgasari can simply dash into the bubble and unload its weapons.
Overall, the Bulgasari has enough firepower and durability to be a heavy robot, completely outclassing its medium counterparts. In that respect, the Bulgasari is by far overpowered for a medium robot, and should be placed in the 'heavy' category, where it would be more balanced. As for the Shocktrain, while its high damage and decent range makes it a great weapon, its exorbitantly high cost (the same goes for the Bulgasari) and chain effect disrupting teamwork justifies its unpopularity with many players.