Like Sam said, there definitely needs to be more of an emphasis on CM Florges when assessing its viability as imo it's Florges' best set right now. For a long ass time, Florges has been considered a mediocre wish passer due to its middling HP stat, meaning that bulkier pokemon really didn't recover all that much when compared to a wish from a Blissey or even an Aromatisse. However, Florges retained its lead in the viability race because of its ability to check two things, Starmie and Blastoise. And then ORAS came around and Florges received Synthesis, a neat tool that many (including myself) simply wrote off in favor of the more traditional Wish set. Over time, CM Florges gained hype and then lost hype and is now gaining it again for its presence and reliability as both a bulky win condition and a defensive component of a team. What CM Florges does opposed to its counterpart, Wish Florges, is it makes everything a whole lot more complicated for your opponent in the same way that every bulky set up mon does. They can go right to their check like Cobalion, but then they might take a whopping 40% or so, making them less reliable in the future. The alternative is to let Florges Calm Mind to the point where their check is literally going to die upon switch in if it takes an attack. This forces a series of 50/50s, stacked in the Florges user's favor, or it requires a pokemon to be sacked.
Of course, what if teams have more reliable checks than Cobalion? Well Florges operates the same way that any other bulky set up pokemon does in this tier. It simply wears them down with repeated hazards switch ins and making them take Moonblasts (off a strong base SpA stat too). In fact, Florges is more reliable at wearing down its counters since it never sleeps to recover its health, unlike Snorlax and Suicune. This means it is always difficult to obtain a free switch into Florges. However, there are pokemon that do come in reliably, namely Crobat, Beedrill, Doublade, Nidoqueen, and a few others. 3 of these are vulnerable to spikes and the other is weak to rocks, letting Florges play the long game and outlast them all since only one has recovery. Also, a neat little set that I have experimented with is offensive Calm Mind Florges, luring the aforementioned pokemon while still maintaining a solid Hydreigon counter that doesn't fold to Fire Blast from Hydreigon. I run near max speed and max SpA with Psychic, MB, CM, Synth and its pretty sick. Anyways, like I was saying, Florges has very solid and reliable staying power with Synthesis over Wish (no roar healing denial) and it can very easily play the long game and force its counters to take hazards repeatedly to the point where you can't call them counters anymore.
TL;DR: Use Florges with Spikes, its sick. A+