It's just like SRW Z same EX mode with no upgrades and PP usage, and another play through to unlock special mode
Shiiit man I've only played Ex once, I was recalling what I remember not sure if it was correct, I just remember them having almost full upgrades. But I found OG 2 more challenging, and SP parts, SP Regen, Enable, Tornado Blade FTW.
Also I think SRW Z would be the most challenging on EX though I never finished it.