@EMI_Eklypz I get the frustration. 100 cost special rule is one of the most restricting rules we get, like Duck said. What it pretty much comes down to is “does my FL beat yours?” so fast FLs or ones which can sweep a bunch of monsters often come out on top.
For a special rule like this one you have to build around what works. Finding that is not always easy, but if your teams are losing lots then you need to save those ideas for another time, when the special rule isn’t on.
A meta that revolves around just a few teams everyone plays is one of the easiest times to play. You can build something which counters those and do very well with it.
For example, I made a team using Aethereon, Regalion and two protectors in a row which perfectly countered Poseidon teams (no GT or single stun revenge), dolphin teams (no killer weakness target), Cani piercing blow teams (forced to hit protectors) and the slower ones with double piercing hitting + GT (seal then no GT or metempsychosis). The Nauti + Aura teams could kill only one of my monsters then had very little more to come back with (Sherloid 5th tended to ruin them) so the only team which could do nasty things to me was Nova enrage.
I did 20-25 battles with my team and lost 3: where I messed up, where I met heavy anti-protector stuff (Orca + Ankou) and where I met a Nova enrage team that had a good team to back it up. So it was 85%+ win rate with a totally unique team, built as link holy + special rocks with a bomb curse combo (Chronotitan + Aethereon).