@MrKritiek I agree with the base Yeti and Dandelion not needing a nerf. In my opinion, they are really fair without any upgrades.
I believe that the main issue with these abilities is the upgrades and spammability of it. I think that this is an example of a flaw in BFN, the upgrades.
The upgrades that make certain abilities cheap like No Fail pail/Head Pot-tection and the speed upgrade for Dandelion and Yeti are not fundamentally balanced. There should be a small downside with these two abilities.
Firstly, have No Fail Pail/Head Pot-tection give lower the damage for both the Wildflower and TV Head, and the explosive abilities. The Explosive abilities would go from 125 damage down to 75, but their health would be increased to 40-45 to compensate. This would make it so these abilities are better for scouting and getting burst damage in so you or your teammates could make a push or get the kill. Wildflower and TV Head would only get 1-2 less damage to their primary. This upgrade would better designed for a pseudo tank/defensive role, allowing these new characters to act like a flex character from other games such as r6 (Rainbow Six Siege) with more variation in playstyle.
Secondly, the speed upgrade for the Yeti and Dandelion. This does need a downside. I believe that for the speed increase, the Yeti and Dandelion should have 10-15 less health (and with Head Pot-tection and No Fail Pail, 20-25 less health) and has an increased consumption rate. This would make this ability much more suited for damage in more close quarters areas, but much worse at mid to long range. It would also make it so the range is pretty limited. Additionally, there would be a fair amount of counter play as it is much weaker health-wise compared to other build variations.
The Final thing to mention is the spammability. The only real solution is to increase the cooldown time, but right now I believe if the devs change the upgrades similar to what I just mentioned, then they most likely won't have to change the cooldown.