What type of Jaden from Season 4? I thought he had his S4 coat... Do you mean when he gets Yubel's heterochromia? The more visible costume change for GX would be like Syrus or Chazz really. But I agree with this! It would be fun to have options
That's a silly idea because the characters barely did nothing in this game beside appears in the bottom corner of the screen. As anon said above, this idea is more suitable for RPG & fighting game that allow you to see characters in their full form.
Still gives you a bit more variety in PvP. Any amount more variety is good IMO. Not seeing every single Kaiba Beatdown deck with the same Battle City Kaiba would make it a tad less monotonous.
Doesn't help that a lot of characters like Crowler and Arkana that are commonly used DON'T have in-canon alt. costumes, but eh.