Does IOTA or Byteball share any of their codebase from each other?
Not even a single line.
Iota is basically a scam, or vaporware, very big promises and little deliveries. See latest events where a few people who had bought iotatokens lost them because they failed to "claim" their tokens again.
Byteball is in livenet/production while iota is still developer-preview/beta only, hence consensus is decided by milestone-databases.