people keep braging that x23 is going to be a threat, but i have failed to see someone truely implament her yet
Non-existent throw game, terrible aerial hit confirmations leading into no real damage and heavy assist requirement. Essentially Jill without an invincible special move that leads into a full combo. X-23 is mostly dangerous because of her unblockable that can wipe out a team but it's still a gimmick and requires work from other characters on the team as well.
Plus other oddities with the character that hold her back. Pretty much any rushdown character that can't convert from throws without an OTG assist and has trouble getting damage from SJ height is not really worth picking in this game IMO. Felicia is like a tier above X-23 because of this, she is more reliable.
Also on the topic of Iron Man the only 3 times its worth picking Iron Man is in the following situation:
1) You play Magneto/Drones and you need a beam assist or Repulsar
2) You need a TAC infinite character, a DHC that does good damage and hits from a long distance, a good damaging THC and a beam that keeps the opponent standing. So like if you are playing Nova and you need a beam, you are better off playing Iron Man than Doom.
3) You already have Doom on your team for missiles but you need a durable beam (like in a team of Spencer/Iron Man/Doom)
There are very few situations in the game where you absolutely NEED Repulsar. I am sure people will experiment with the assist against MorriDoom but there aren't enough teams that can make great use of it. A lot of the characters that can make good use of it are some of the Mid tiers like Sentinel, Rocket Raccoon etc. In most cases you would want Unibeam over Repulsar but even so... Plasma Beam is going to be preferable because of the positioning from where Doom comes out.