I have two things that piss me off in For Glory:
1. Taunting after taking the first stock. To me, this wouldn't be much of a problem if you could verbally communicate with other smashers. With communication, we could know whether or not a taunting competitor is taunting to joke around and have fun, or be a completely arrogant imbecile. So because we don't have the luxury of efficient communication, I can't detect whether or not the person taunting is just being funny or is rubbing his/her success in your face. Not only that, but it just isn't smart. There's some people who play better when angry, so you can end up screwing yourself. Or, your taunt could last to long, and the person who was KO'd could punish you with a combo or a heavy hit if the person is fast enough. I personally think taunting was made for when you're playing with friends and want to be funny. My suggested alternatives to prancing around like an idiot is crouching/jumping in an erratic fashion (kinda rude, but not as blatant), dodging and pivoting, or charging up moves for the next stock (smartest alternative). After the second stock, go crazy. I don't care. You won.
2. Not punishing missed rests correctly. As a Jiggs main, I've done my fair share of rests. Due to me being somewhat inept at sm4sh, and just plain horrible decision making, I miss rests a lot. What I've noticed over the past month is that BARELY ANYONE KNOWS HOW TO PUNISH A REST AND IT'S GETTING ANNOYING. When I miss a rest, people either wake me up with a measly jab (which is very unsportsmanlike), a weak tilt, or trying to combo me off the stage. That's not how you should do it. I don't see why no one would take the obvious advantage of rubbing my miss in my face by unleashing a fully charged smash or a turnaround Falcon/Warlock Punch. It's just completely disrespectful for someone to punish with a jab or tilt because it shows that you don't take your competitor as serious competition and want to KO them "correctly". It's also not smart because it gives the competitor a second wind at winning the stock/match and, as I addressed earlier, can screw you by making the competitor angry and cause them to play better. Combo punishes are just dumb because Jigglypuff can easily maneuver out of a combo, and usually the people playing the game aren't adept enough to do the combo effectively. F-smashing or Falcon/Warlock punching is a much better choice because it racks up damage, which on a Jigglypuff, is very valuable due to her being the lightest character and the easiest to KO (of course meaning that a charged smash could potentially KO at low percentages). I just hate when people don't make the obviously better choices. Punish me dammit.
Tl;dr If you taunt after taking the first stock, or try to style punish a missed rest in For Glory mode, you are a complete and utter Neanderthal.