it's sad truth, some time ago i tried to find inspiration to get some dungeons achivements (well im ouginak main so he is a must to be in team) aaand yeah i can't hide it, ouginak is pretty useless in many achivements( maybe not useless but any other class probably would be better, maybe sac would be even more useless in some cases but not sure). So let's say i was looking for video with protozoror statue or barbaric, aand if i remember right there was only one different video that didn't use elio tactic, eeevery single video used the damn panda elio enu... (and usually iop/cra ofc). Most videos are done pretty much same compositons (usually cra enu panda eni or sth similiar).
I also tried to abuse lavasmith aaaand do vortex score + impertinence in the same run(payos and some other shit) but as I am lazy after ~20 fails I decided to do it seperately with different tactic.
Similiar with ilyzaelle i saw many 'autowins' using elio but was that really autowin? they kinda blitzed her to 75% hp t2.. it was boring. So i decided to blitz to 75% hp 1st turn(using panda elio ougi(agi +stripping) and usually 2 random chars) (i actually made elio just because i thought it might be useful for me) and it was probably the only dungeon that i used it XD
I started to play in march 2017, i made another 3 chars few months later, i found it quite hard at the beggining to do some dungeons, but i managed to earn kamas, get better items and i got some basic info about monsters (its not really necessary to know everything, just basics like does it attack in melee/mid or high range). For example doing QoT first time took me like 9 hours to understand pretty well what's going on. Some compositions just fit better for certain dungeons (actually achivements cuz with good enough items its kinda impossible to fail a dungeon for simple pass without any achivements (u'll eventually get it done after some tries (maybe even 20-40)). For example i went with 2 mp rape chars + dmg cra + ougi for protozoror statue or barbaric. But for score i went with sac panda ougi eni and just and just tanked it. Both ways are possible to complete dungeon (well cc team + barbaric wouldn't be good idea for proto).
Most duos are possible to get done easily with anychar + panda/enu/cra (not even mentioning that for example @masik233 can solo em all with rogue XD) but let's say not many ppl are such tryhards so these chars are useful.