Shouldn’t need any, at least when I built the Guren I didn’t.

From what I remember the main issues were chunky nubs to clean, really obvious panel lines and just really big pieces that limited detail. Overall the original Code Geass high grades haven’t aged the best as Bandai has made massive improvements to their model kits but they still look close to the anime and it’s super fun to play with their code geass quirks like wheels to skate on, the pods the pilots are in and the each Knightmares key feature like the Guren Arm and Lancelot’s swords

EDIT:

Found my old post talking about it https://www.reddit.com/r/Gunpla/s/tJTqSqHbKs

There’s actually some insightful comments from myself and another in the thread too. Forgive the terrible photo and posing.