Late again
For what it's worth, I am in support of moving Thunderbolt to Allowed and Scald to Disallowed, if the issue should come up again. I also don't have any issues with anything else in the Allowed/Required lists, save one. Why, exactly, are so many moves suddenly "required"? I was under the impression that this was merely for absolute flavour requirements, such as Toxic and Hidden Power, rather than moves such as Thunder or Sludge Wave, which are not necessitated by either of Mollux's typings or the moves that it does actually require (there are large numbers of Poison-types without Sludge Wave). I am not entirely sure why this is the case but it would appear to be putting a rather large constraint upon those who might actually not want to include Electric-type attacks or Acid Spray in their movepools. These are things that are supposed to differ from movepool to movepool to create a balanced slate, and I'm surprised that the very opportunity to reject them has apparently been rescinded. The Required Move section ought to look like this:
Required
Fire Blast
Flamethrower
Hidden Power
Overheat
Sludge Bomb
SolarBeam
With the possible omission of SolarBeam should it be desired.
With regard to the Pending moves, Brine ought to be disallowed, if only for the same reasons as Scald - while it might be weaker than Hidden Power Water (just) it's still a usable attack. To that end, Mud Bomb and Mud Shot should also be disallowed, as both make for viable alternatives to HP Ground that also enable you to select another Hidden Power type. These three moves are all of a type that hit some of the Pokemon that are supposed to be threatening super effectively; while they are not powerful, perhaps, they are distracting and unnecessary, while serving no practical purpose against the Pokemon that we are actually supposed to be beating.
Dark Pulse, Shadow Ball, and Signal Beam I am ambivalent on. Assuming we get Thunderbolt, then Jellicent and Starmie will be taken care of regardless, and most other noteworthy Psychic- and Ghost-types in OU are dealt with more effectively by STAB Fire Blast - with the exceptions of Latias and Latios. It may actually be worth adding Dark Pulse or Shadow Ball just for them - or rather, just Latias, as both LO Sludge Wave and LO Shadow Ball will 2HKO Latios, whereas LO Shadow Ball has a chance to 2HKO with Latias, even through Leftovers, whereas LO Sludge Wave can never 2HKO without Stealth Rock or some other prior damage. This may not be such a bad thing, however, if we are trying to encourage the use of its Poison-type STAB. So, I would incline towards "disallow" for these three moves at present, as they are all quite niche and distracting, while STAB Sludge Wave or Sludge Bomb in the same slot has arguably more utility. I wouldn't see any harm in allowing them, though. Hex also falls in this category.
Eruption has a rather nifty relationship with Dry Skin, in that its power is decreased regardless of whether you use it in the rain or the sun. Switching your Mollux into a Water-type attack heals you and also increases the power of Eruption, which is nice, but if you happen to be facing a sun team, then Mollux's HP is decreasing every turn. As a general note, Eruption is only stronger than Fire Blast when Mollux is above 80% of its health - thus if it switches into Stealth Rock once, it's less effective than Fire Blast. To carry it further, it is only stronger than Flamethrower when Mollux is above 63% of its health. I don't see Eruption being too powerful at all - far from it, it's a very interesting option that arguably takes advantage of one of the advantages of Fire, in its access to high-powered STAB attacks, and could also increase Mollux's viability on sun teams (okay maybe not, but still). I'd say allow this move, please.
Lastly, Charge Beam and Power Gem. I know that some people are trying to get Mollux to have Nasty Plot or Tail Glow or whatever, which I disagree with, to the extent that I don't think that boosting moves are entirely necessary or even a good idea here - especially when said boosting move happens to be a super effective attack against Pokemon who are both very common and can't hurt Mollux with their STAB moves. It's not a great idea. You may well say "well why not?", but I don't consider that to be a good attitude to take here. The non-attacking moves discussion will bring what it does, but for me, I'd rather avoid a boosting move of this nature. I won't argue strongly against its inclusion if people really seem to want it, but I'll just urge here the value of moderation.
As far as Power Gem goes, it's just a Hidden Power Rock substitute. The downside is, of course, that you need not actually use Hidden Power Rock any longer, which is again freeing up our Hidden Power slot for something else. And I see that as bad, largely for the reasons that I see most of the good coverage moves here as "bad". I would like to see the Poison-type STAB being made use of to an extent - I accept that one slot will be required for Fire-type STAB, another likely for Thunderbolt, Thunder, or SolarBeam, depending on the team strategy, and one more for a Hidden Power of some description, be it Water, Fighting, Ground, or whatever. Assuming that Mollux will be capable of running a 4-attacking-move set, this leaves one slot for a Poison-type move... or for another coverage move. For that reason I do not want to see Power Gem, as there is far too much use for it in that extra slot. Be it Sludge Bomb or indeed Acid Spray, I would like to see a Poison-type attack as a viable option on at least some sets. So, disallow Power Gem please.
Finally, to finish up, simply because some people seem to be forgetting it, here's the threat list again:
Deck Knight said:
THREATENED BY
Rock- / Ground-types
Tyranitar
Terrakion
Landorus
Dugtrio
Gliscor
Other
Offensive Heatran
CAP 3
Dragonite
THREATENS
Water-types
Politoed
Tentacruel
Jellicent
Other
Defensive Heatran