B.E.S.

B.E.S. is a series of Monster Cards usually identified by having B.E.S. in their card name, but also include "Big Core". B.E.S. stands for Bacterium Empire Ship. The B.E.S. cards are based on the bosses of the Konami video game Gradius. They were used by Lorenzo in the anime.

Playing Style
B.E.S. cards effects include putting counters on them when they are Summoned and cannot be destroyed as a Result of Battle. After battling a monster, a counter is usually removed at the end of the Damage Step, and if they battle without a counter they are destroyed at the end of the Damage Step. The counters represent the "shields" on most bosses that represent their much higher ability to take damage than normal enemies. Of the B.E.S. monsters, only "B.E.S. Covered Core" has a chance of not losing part of its shield - representing the enemy attack only striking an invincible part of the exceptionally well-armored boss rather than the vulnerable location.

The main strategy of this deck is using "Boss Rush"'s effect to Special Summon B.E.S. monsters and inflict Continuous Direct Damage to your opponent thanks to "Cyber Summon Blaster".

Another strategy is an offensive beat down, using cards like "Mausoleum of the Emperor" to summon "The Cores" when Boss Rush isn't on the field, or use "The Creator", "The Tricky", "Cyber Dragon", "Cyber Dinosaur",and "The Fiend Megacyber" to make summoning the Cores a whole lot easier. "Cyber Phoenix" can offer "The Cores" protection from being targeted by your opponent's effects, and when it's attacked and destroyed, you get to draw a card.

Perfect Machine King can be used in this deck, because the main theme here is Machine and it gains 500 ATK for each machine on the field, making it a 4700 attacker if your field is full (of Machine-types). Trap Monsters such as "Embodiment of Apophis", "Metal Reflect Slime", and "Zoma the Spirit" can aid in summoning "The Cores" and virtually eliminate using other monsters as well. They can be lifesavers if your opponent removes your monsters from play or bounces them, as otherwise "Boss Rush" would prevent you from defending yourself. If you use "Mausoleum of the Emperor", you might want to include a few "Life Absorbing Machines", so you'll gain some life points for each monster you summon using said field spell.

"Jinzo" and "Royal Decree" can be a lifesaver for this deck because you can freely attack and summon without worrying about "Solemn Judgment", "Royal Oppression", "Mirror Force", or any Counter Trap Cards for that matter. Depending on how you build it, this deck can become a pretty cool deck for casual and leauge play. You can also discard "The Cores" to the Graveyard via "Snipe Hunter", "The Tricky", "Foolish Burial", etc. and then special summon said cards to the field. Also highly usable is "Pot of Avarice", because it gets back any of the B.E.S. cards back into the deck to be re-used with "Boss Rush".

The only weakness of this deck that it's impossible to Normal Summon as long as "Boss Rush" is on the field ; this is why "Cyber Dragon", "The Tricky", and Trap Monsters are useful in this kind of Deck. Plus, you must try to keep at least 1 "Boss Rush" on the field or all your hard work fails - "Magic Reflector" is the perfect card to protect "Boss Rush". However, when the Deck works, it can be quite powerful, as "Boss Rush" ensures that you have a constant supply of high level monsters, and any actions your opponent takes to destroy them will simply allow you to summon a new one. As well, the fact that the B.E.S. Monsters constantly destroy and replace themselves gives this deck a slight edge on Alien and Venom decks, as they will be unable to build up counters on your monsters.

Also, if you know how to do it, B.E.S. can work very well with Fusion or Synchro-based decks. With tuners like "Krebons" and "Plaguespreader Zombie", Synchro Summoning should be a breeze. "Chimeratech Overdragon" and "Chimeratech Fortress Dragon" can be pretty formidable in this deck w/ the large amount of summoning going on. Using "Future Fusion" and "Overload Fusion" can get out 2 "Chimeratech Overdragons" for an easy OTK.

Synchro-Based
Use these cards if running a Synchro-based deck.
 * Stardust Dragon
 * Thought Ruler Archfiend
 * Krebons
 * Plaguespreader Zombie
 * Mind Master
 * Psychic Commander
 * Emergency Teleport

Fusion-Based
Use these cards if running a Fusion-based deck.
 * Chimeratech Overdragon
 * Chimeratech Fortress Dragon
 * Overload Fusion
 * Power Bond
 * Future Fusion
 * Elemental Hero Prisma

Monsters

 * B.E.S. Crystal Core
 * B.E.S. Tetran
 * B.E.S. Covered Core
 * Big Core
 * B.E.S. Big Core MK-2
 * Cyber Dragon
 * The Tricky
 * Spirit Reaper or Marshmallon
 * Jinzo
 * Snipe Hunter

Spell

 * Boss Rush
 * Mausoleum of the Emperor
 * Terraforming (If using Mausoleum of the Emperor)
 * Monster Reborn
 * Pot of Avarice
 * Lightning Vortex
 * Brain Control
 * Soul Exchange
 * Foolish Burial
 * Monster Reincarnation
 * Heavy Storm (you have Jinzo)
 * Cold Wave
 * Ancient Forest (your monsters are usually summoned without shields and die with a single attack anyway)
 * Pot of Benevolence (recycle B.E.S. if you need more summon and have Jinzo on the field)
 * Limiter Removal

Traps

 * Royal Decree
 * The Transmigration Prophecy
 * Reckless Greed
 * Narrow Pass (You will be unable to Normal Summon when Boss Rush is on the field, so this won't affect you)

Weak Against

 * Burn Deck
 * Different Dimension (D.D.) Deck (Boss Rush does not activate if the B.E.S. monster is not sent to the graveyard)
 * Final Countdown Deck
 * Rock Deck
 * Bounce Deck

Related
It should be noted that there are some cards, such as "Brain Golem", that are Bosses from Gradius, but are not a part of this archetype.