Ugh, look up the definition of counter before you go saying something like that. If by "counter" you mean "revenge kill", there's a massive amount of things that can "counter" Syclant. If you need 10...Crobat, Swellow, Ninjask, and Aerodactyl can easily do it without a Scarf, and with a Scarf the list is massive (Azelf, Garchomp, Salamence, Infernape, Electivire, Flygon, the list goes on for a long time). Syclant's stats aren't anywhere near so impressive that it can OHKO everything in OU, either.The 600 dragons are all countered by a bulky or fast Ice Beamer, and Metagross and TTar are countered by fast sweepers with a super-effective move. Those obviously are very large pools of Pokémon. Gengar is countered by Weavile or any bulky Pursuiter, and other fast sweepers such as Weavile, Jolteon, and Aerodactyl are countered by anything bulky.
Wow, Ghost/Fight is dominating. At this point I sadly doubt there's really a case for Grass/Ghost, so may as well get on with discussing what Ghost/Fight will be like.
One concern I have is that we'll get another tank like Dusknoir - we already have two ghost type tanks and several special sweepers (I was actually hoping for a bulky special-ish sweeper/supporter for a Grass/Ghost, maybe something along the lines of Celebi, but eh), but we don't have a single ghost physical sweeper. Also, care will have to be taken that this isn't overpowered - Ghost/Fighting is an obscenely good type combo both offensively (NOTHING can switch in without fearing a neutral STAB and many of the biggest walls like Cress and Bliss are hit SE) and defensively (several very useful resists and two out of it's 3 weaknesses are fairly rarely used for offense).
As for stat spreads, I obviously don't want a tank-ish spread. Something that's decently powerful on the physical side, slightly bulky in both defensive stats, and has slightly above average speed would be my top pick (in general, think a toned-down version of Garchomp's stats). Like... 90/120/85/80/75/95. It still has enough defense to switch into Heracross safely but many neutral STAB attacks will be enough to 2 or 1HKO it.
Exactly why it would be perfect for a Banette evolution >_>So make it slow and frail, if you must make it at all.