One of my friends wants an ultimate that changes between 2 skill sets or 2 races.

For example:
Race 1 / Skill set 1
Skill 1 - player_spawn
Skill 2 - player_victim
Ultimate - switch to Race 2

Race 2 / Skill set 2
Skill 1 - player_spawn
Skill 2 - player_attacker
Ultimate - switch to Race 1

I can't figure out how to even begin to code the ultimate. Since everything is switching mid round which I don't think can work?

Hmm... Perhaps you could script player Events which check the player's key values, simply set each skill to be Spawn -to turn certain values "on"- then have more detailed events scripted for if a certain value is "on", and finally, when the ultimate is used, switch all of the "on" values to "off" and an entirely new chain of "off" values that are already set to check in player Events to "on"...

To be honest, it's a little beyond me as far as coding goes, but I'm sure some of the more experienced coders could do it. xD