pro:
great support
good farm for mf(cauz janna takes no last hits)
good farm for kennen cauz solo lane
good mid push(heimer)
fast jungler(rammus)with fast gank and lane support
one of the best tank cauz of his taunt and stun/slow
aoe heal(janna) aoe dmg(kennen)
janna can push enemies into kennens ulti with her own ulti

contra:
squishy team(mf, kennen, janna and heimer)
no melee dps
no global

sorry for my bad english, but i´ll try
lets go!
fast shop for all, clairvoyance near enemy nexus. janna and mf bot lane.
rammus starts at blue buff. heimer takes mid and kennen top solo. both must guard rammus. we need no rush from enemy at lvl 1.use clairvoyance now to guard rammus too.
heimer and kennen at 1:55 back to lane. rammus can start jungle and soon ganks.
janna supports mf with shield. no last hits for janna only assist mf with some hits.
so you got 3 lanes with nice farm. janna goes warding, later she use magic wards and oracle for map control. use clairvoyance everytime, maybe you ll find the enemy jungler. or steal the other buffs with rammus, but care they could place wards too^^
in teamfights janna could try to flash behind the enemies, use her ulti and drop some champs in kennen aoe ulti. it works fine:) rammus must taunt the enemy dd. heimer and mf ulti and you ve won the clash...so push push push

escape for everyone( ghost or flash)
clairvoyance for safe lanes
clarity from heimer for your mana champs
teleport from heimer to push or defend fast a lane
exhaust for auto atack champs like trynda
ignite for champs like ww or mundo
smite for a fast jungle and maybe buff/baron/dragon steal

all needs banshes veil
janna goes many aura items
kennen and heimer ap items
mf dmg/crit
rammus normal tank items

maybe they ll bann your champs, so you must change to:
rammus : amumu/malphite/shen
janna : sona/taric/zilean/morgana (full support)
mf : corki, kog maw, ashe ( range dps )
Heimer : sivir(ap), yi(ap), malzahar, morgana ( you need fast push in mid)

play some games with this teams and you are rdy for ranked