Awesome, thanks. Some things I've noticed about grass mono.
Nov (2.30%) -> Dec (2.39%) -> Jan (3.13%): This is great to see that grass is growing in usage.
If every type was used equally, it would amount to about 5.56% usage, so its well on its way.
EDIT: I forgot to mention about type match-ups.
Terrible Matchup : Dragon, Fairy, Fire, Flying, Ghost, Steel ---> Fire, Flying ---> Bug, Fire, Flying, Steel
Bad Matchup: Bug, Dark, Fight, Normal, Poison, Psychic ---> Bug, Dark, Dragon, Fairy, Fight, Ghost, Ground, Ice, Normal, Poison, Psychic, Steel ---> Dragon, Fairy, Fight, Ghost, Ice, Normal, Poison, Psychic
Neutral Matchup: Ground, Ice, Water ---> N/A ---> Dark, Electric, Ground
Good Matchup: Electric, Rock ---> Electric, Rock ---> Rock, Water
Awesome Matchup: N/A ---> Water ---> N/A
I guess you can see from the general tiers above that Grass still doesn't fair very well against a majority of the metagame.
Looking at the top 12 for grass over the last three months we can see that:
TOP 12: (note bold means new entry into top 12, green means the pokemon has risen in rank and red means it has fallen in rank)
1. Ferrothorn (90.52%) ---> Ferrothorn (89.92%) ---> Ferrothorn (88.50%)
2. Breloom (90.07%) ---> Breloom (80.54%) ---> Breloom (83.74%)
3. Shaymin-Sky (78.90%) ---> Shaymin-Sky (76.38%) ---> Shaymin-Sky (79.65%)
4. Venusaur (61.72%) ---> Venusaur (65.45%) ---> Venusaur (77.91%)
5. Ludicolo (45. 37%) ---> Cradily (46.97%) ---> Serperior (42.34%)
6. Cradily (39.37%) ---> Sceptile (36.87) ---> Cradily (39.17%)
7. Sceptile (38.38%) ---> Whimiscott (28.01%) ---> Sceptile (28.50%)
8. Rotom-Mow (32.69%) ---> Rotom-Mow (27.22%) ---> Rotom-Mow (25.82%)
9. Whimsicott (23.97%) ---> Ludicolo (24.98%) ---> Whimsicott (23.64%)
10. Gourgeist (14.64%) ---> Roserade (20.32%) ---> Ludicolo (18.20%)
11. Shiftry (13.23%) ---> Shiftry (17.56%) ---> Celebi (16.49%)
12. Celebi (8.66%) ---> Celebi (14.76%) ---> Trevenant (11.82%)
So essentially, the top 4 haven't changed. Gourgeist fell out of the top 12 in December and now sits at 18th spot with 2.99% usage. Roserade moved into the top 12 in November only to drop out again in January to sit just outside at 13th with 11.72% usage. Shiftry dropped out of the top 12 in January and now sits beside Roserade at 14th with 10.04% usage. With Roserade and Shiftry dropping out of the top 12, the new additions of Serperior and Trevenant have made their way up. Trevenant had been borderline in 13th position for November and December, but Serperior rose from 30th spot with 1.06% usage in December to 5th with 42.24% usage thanks to the release of Contrary. It is also interesting to note that in the last three months, pokemon mentioned above, no other grass type has been above 10% usage. There isn't much else to say apart from the mega forms stays more or less the same. Venusaur was 62.91% in Dec and 75.85% in Jan for Mega usage while Sceptile was 32.50% in Dec and 18.97% in Jan. The fall in Sceptile's usage as a Mega is likely due to the rise of Serperior which basically does the same job without a mega stone and with free boosts (obviously it can't run physical sets though, and isn't as fast, giving Mega-Sceptile it's niche). I won't go into movesets as that would take forever but I'm sure there is lots of interesting stuff to say there as well.
ASIDE: I would also be interested to know, with three months worth of stats, whether there is any chance of an UU monotype tier being formulated, using monotype stats instead of OU stats.