BattleTech in general is built around giving you tools, and it's up to you if/how to use them. The Inner Sphere uses lances of four, but there are plenty of canon examples of understength/overstrength lances, forces with missing units (damaged/destroyed in previous engagements), etc. Or the occasional oddball unit.
So rules wise, there's a lot of freedom. Nothing says you have to use lances. It just tells you what lances are, and that the Inner Sphere uses them. (There is a requirement that any formation has at least three members to get any benefits, that is a specific rule).
Whether or not you require lances, allow exceptions to the force building, etc are up to you, your group or the format you are playing in. There's no Alpha Strike wide ruling (beyond the must have 3 to get formation benefits).
Personally, I'd have at least the option for an understrength "final" formation. Even if required full formations for the organization chosen, I'd give leeway on the last formation to take the remainder. Especially with other requirements that I'd be stricter on (PV limits). But that's just a personal opinion.
Hi nckestrel. Thank you for the response. But a few additional questions after I let my group see your answer. Most of our issues come from the "overstrength" term.
Does this mean that extra units are allowed/counted/legal in an IS lance, Clan star, or Comstar Level 2 formation?
For example, if I add an extra unit(s) to a 4-mech IS lance, 5-mech Clan star, or 6-mech Comstar formation, are all mechs eligible/counted/legal for the formation bonus?
Or is it only the 4 mechs in an IS lance, 5 mechs in a Clan Star, or 6 mechs in a Comstar formation that are counted for the formation bonus? Extra "reinforced" mechs in the lance, star, or Comstar formation are not counted?
Our gaming group loves formations, and this is a standard part of our game along with SCAs and SPAs. However, as one of the group leaders, I'm concerned that adding reinforcement/extra units to a standard lance, star, or Comstar Level 2, and making these extra units eligible for the formation bonus may cause the formation to become OP.
Personally, how do you rule this out? Since you're the moderator/rules writer, your suggestion would have a heavier weight on the interpretation and implementation of this rule than player understanding/interpreation. That would actually be better as your interpretation/suggestion would be more official.
Please advise. Thank you!