For Ver. 3 Any% is there a Reason why everyone plays on GCN or is there no difference between the Dreamcast ver. and the GCN version?

The item duping is gamecube only so that's why glitched it's ran gamecube, I don't know about glitchless tho

Is there a version 3 for Dreamcast? I thought Dreamcast was only version 1 and 2

Dreamcast is Version 1 and 2 (increased level cap and Ultimate gamemode), Gamecube/Xbox is Version 3 (Ep1 is a remake of Ver 2, with the addition of Ep2), and Blue Burst (PC) is Version 4 (remake of Version 3 with another episode of content).

All console versions of the game (except Plus and maybe GC 1.1) have item duping. v1 let’s you clip through doors with attack combos. The Dreamcast versions force you to activate the ruins unlock pillars on a second iteration of the first three areas (respawning mobs and locking doors but preserving loot on the ground). That is mitigated in v1 because you just clip through the ruins entrance door anyway so you don’t ever go out of your way for a pillar.

The numeric mechanics in Dreamcast are different, notably RAcast cannot equip Saber at level 1 until v3. This significantly slows things down for RAcast and you’ll observe the best run is a HUcast instead, while RAcast runs are currently opting to stack a second time. Weapon attribute% works somewhat differently and you may be stuck buying weapons with -%.

No quick menu in v1 makes the game more physically demanding for doing things like switching weapons.

Overall Gamecube is the more accessible version, and faster for various reasons. v1 is fun because of the unique fun things it brings and just being a different flavor. v2 trades door clipping for a quick menu and it’s not a good trade for speed so no one does glitched runs for that.

For Glitchless, it’s mostly v3 for the same reasons and also the Forces are a lot weaker and physically slower on Dreamcast.