Your right, there is no real use in running a single hammer, I agree. In my build, I run two hammers. It works. But playing with two hammers is a style of play thing. It forces you to hold the card in your hand as long possible, which gets annoying.
I think the play would either be two or 0 like you said, I just don't have the space for it, but it is something I would be running if there were 65 cards allowed
Honestly, the best way I've figured out how to handle the match ups is to run a single copy of weakness policy. Instead of going Mega early you run head ringers and use a single manetric ex with a weakness policy. This helps with the Lucario and landorus matchup. With a donphan matchup, I try to get it out to buy enough time, sometimes the tool drops on Donphan and sometimes it doesn't. What I want to happen is have another M manatric or Articuno waiting on the bench to help with mop up. Either way, it's a tough matchup, unless you go bats Manetric, which make the matchups quite a bit easier.
Eh, I'm not too keen on weakness policy. My deck is very structured around the Mega. If you don't get it out T2, T3 latest you are either dead drawing or your opponent got a mad setup. Weakness policy kinda goes against that as it ends your turn. Sure, it's great for the basics...or is it? Many Fighting Type decks rely on 2HKOes anyways, IE Mienshao, Donphan, Lucario, and Landorus. Despite not having weakness, it's not really a big problem for them. As well, most of those decks run Xerosic or possibly a megaphone. You'd have to run a significant number of Weakness Policy for it to matter. If you run 1/2, you'll never run into it when necessary. But if you run 3/4, you are significantly hurting your deck; drawing into it against matches where it's useful and taking out support cards for techs is never worth it. Lastly, they made Flash energy for this reason! It solves all of the problems I listed above and provides (L) energy! Outside of not being able to get it back from the discard (but same as tools) and it can be xerosic'd (but so can weakness policy) I feel as if Flash Energy is already the go-to weakness solver.
I do recognize that Flash does only apply to electric pokemon, so it wouldn't work for Regice, Articuno, and Shaymin EX. But in all honestly, when does weakness really come into play with >140 HP pokemon? Metal and electric types are already one shotting those little guys, so TBH it's only really relevant to Manectric EX somewhat.
I don't know what your water build is but I've been running a 2 copy of regice, and a 3 copy of Articuno (AT). Though, I still find bats Manetric to be the better variant in this Meta.
I run 2 Regice and 1 Articuno. I think that both versions have their benefits. I think that Bats makes many decks that were once meh not so meh. But against my version (water), it barely helps. I bring up Regice and they basically lose. Then I one shot all of their Shaymins and Bats on the bench with Articuno or Manectric for easy game prizes.
Last note, 16 is a strong finish. In my opinion you played really well to make 16th. Especially if you were playing with competitors like Frank Diaz. Congrats!
Thanks, I was so close to winning...next turn ugh! But the better man won so I can't complain haha