Custom client bug
Technically speaking, the roborumble weight classes have no minimum thresholds, only maximum thresholds. Thus, each rumble contains bots not only under its own weight limit, but also bots under the weight limits of other rumbles with a smaller maximum threshold. For example, just because a bot with a codesize of 249 bytes is a nanobot, it is no less a microbot than a bot with a codesize of 749 bytes. This is how the weight classes are structured: nano < 250 < micro < 750 < mini < 1500 < mega < positive infinity. Note that we use < and not <=, which is why we don't allow bots with a codesize of 250 bytes into the nanorumble.