if you want to fight IC's ground to ground blizz versus needles, probably a better idea jsut to hold onto your needles, since needles go pretty quick across the screen and blizz can't be spammed constantly, just wait for the gap. Even if the IC player's nana absorbs the needles for popo (as in she gets hit during blizz recovery). She still is easier to eliminate (which is pretty key for shiek since fighting popo alone is so much easier. I wouldn't advise attempting needle camping though, unless you charge the needles that will hold down the IC player for a certian amount of time. Spamming non charged needles doesn't sound like a good idea, doubt though shieks will do that, but I've seen DSF do it.
Marth's Dtilt is abuot the same range as blizz I think, but also if she is desynced doing blizz, popo can jump over the dtilt and fair marth. but, you could always wait for blizzard close to finish then go for tipper fsmash. It might help to DI out really far with marth to avoid meeting bairs dsmashes and fsmashes. During blizzards and not.
IC players shielding can do the shield upb cancel into blizz to take offense off their opponent and for free grabs. Kinda rare though you get a chance that doesn't put the hitstun on your shield and leave your characters open to freely do it.
My solutions: (Possible)
Marth : don't use dtilt in this matchup, standing A and forward smash outrange too easily, projectiles are weak and you have air superiority. Don't grab in this matchup unless it's solo popo (which is wierd because marth grabs a ton). 80- death % use forward b to launch them possibly into fsmash and such. DI hard out on a lot of moves, when nana is around.
Shiek : horizontal distances aren't friendly to shiek and needle spam, choose places where the IC's have to chase shiek. Use needle turnarounds off high platforms (like bfield, dreamland 64). Bigger may be better for these stages (considering IC's have trouble with air advances unless they're below you). Remember shiek has an easy time fairing IC's and killing them on recovery. Use higher charges of needles, after blizzard. Dual IC blizz leaves almost no time for them to setup moves after that. Single IC blizz will lock shiek down if she gets caught. If you're above IC's they aren't likely to blizz you anyways.
Fox: Space your jumps better than normally, I would say on average use jumps that will reach the back of Ic's or inside all the time, make sure they don't have setup to avoid with WD's. If the IC player has to do solo blizz, tey have to desync by some type of command. you see ground dodge, you're free to jump above the second before the blizz and nair shine. Double blizz will keep him at bay for a short time, but hey fox is an animal and he's quick. Don't be afraid to wait the IC player out if they're using solo blizz and desyncs to approach. Chu does that iceblocks desync jumping approach in order to intimidate his opponent, what if the opponent just empty jumped over all the ice blocks and avoided blizzards waited until an opening and nair/baired the popo?
If any of this helped I hope, not sure.
