Effect: [Your Turn] When this Digimon digivolves into a Digimon with [Myotismon] in name from your hand, reduce the memory cost of the evolution by 1.
Inherited effect: When this Digimon has [Myotismon] in it's name, all your Digimon with [Retaliation] can attack your opponent’s LV4 or lower unsuspended Digimon.
Effect 1: [Retaliation]
Effect 2: [When Attacking][Once Per Turn] You may play a LV4 or lower purple Digimon with [Retaliation] from your trash without paying its cost. Any [On Play] effects of that Digimon will not activate.
Along the Myotismon Route
The EX1 Myotismon has powerful inheritable effect that allows your Digimons with [Retaliation] to attack a LV4 or lower unsuspended Digimon (and yes, being able to attack unsuspended Digimons is a big advantage).
Digivolve him into the new EX1 VenomMyotismon to attack an opponent's unsuspended LV3/4 Digimon (for some board control) while rendering your suspended self quite safe due to [Retaliation], while pulling another [BT2-074] Devimon from your trash.
Myotismon also works extremely well with the starter deck [ST6-12] VenomMyotismon, digivolving cheap at only 2 cost (due to Myotismon's effect) while granting yourself and/or your other Digimons [Retaliation], allowing for very flexible counterattacks!
Meanwhile, [BT3-092] MaloMyotismon is an absolute stunner with the new EX1 Myotismon. By inheriting [Retaliation] from a LV4 Devimon or Devidramon, this Digimon can attack any unsuspended LV3/4 Digimon with [Piercing], and gaining +1 memory in that process (not to mention that his digivolution cost will be cheaper thanks to Myotismon)!
To Anubismon (Or Not)
[BT4-087] Anubismon can offer some support to the new EX1 VenomMyotismon, by granting a revived BT2 Devimon [Haste]. However, the disadvantages of fielding this duo in your deck may often outweigh a Devimon with [Haste].
Solid Pairings from BT-06
In BT-06, there are a few solid choices that can work candidly well with the new Myotismons. [BT6-078] Skullgreymon very flexibly grants [Retaliation], while [BT6-091] Sora & Mimi encourages a LV3/4 Digimon at your opponent's board (to give Myotismon's inheritable effect an attack target every turn).
Technically, any Digimon with [Retaliation] will benefit from the new Myotismon, but [BT2-080] Piedmon in particular can be a natural synergy. Both VenomMyotismon and Piedmon are iconic villians from the first Digimon Adventure anime series, and with wishful thinking Bandai might take the opportunity to give Piedmon a buff.
With both Piedmon and the new VenomMyotismon working on LV4 Digimons from trash, there is a chance that we will get a suitable LV4 purple Digimon in EX1 (another Devimon?) that works like magic. But until then, I'd like to think that the 12-cost to play a Piedmon to be too inefficient in this meta.
Retaliation has always been an effect that is pretty much reactive in nature, but with the new Myotismon it would seem that this humble effect will get a new play. It will be exciting to see what decks and playstyles spawn from one simple Myotismon!