Are there enough Gundam characters/mechs by this point to make a gachagame?
Way beyond enough, and there's already one out right now (Gundam Breaker Mobile), alongside an SD Gundam G Gen mobile game that was announced just yesterday + Arsenal Base, which is one of those arcade games that you have to use collectible cards for. There's also Gundam U.C. Engage which is ANOTHER active Gundam mobile game (UC only) but idk if that one has gacha mechanics.