Can I join multiple teams and play in any match either team has in season 2? I don't see anything in the rules. For example I'm in division 2 can I join a division 1 team and play in their games also? What if I joined a division 4 team?
Obviously you may not. The rules say multiple accounts are forbidden. The possibility to join multiple teams is there so that you can play for example the Custom Maps Cup with a different team than with your regular season team without leaving it.
If a player is playing the Season 2 in two different teams, you should contact the admins like swalk or blind and we will investigate it :)
Quote from rules, "Teams may occasionally use up to 2 mercenaries (mercs). However, said mercs must be of equivalent level of the team (specified by the contest's subrules). The other team can refuse the use of mercenaries in general or of specific players, however it is highly encouraged by ENSL to play all matches as 6vs6."
Mercs are players who temporarily play for a team should that team that could not field 6 players from their own team before their scheduled match. That wouldn't make you a permanent player for that team. Also, say you're in Division 2, you cannot merc for a Division 4 team, as that would make it unfair for the opposing team. Mercs must be on a team in the same division or lower AND approved by the other team.
No team can refuse mercs "in general", only in the case that they feel the merc(s) are better than the team they are mercing for. This was clarified in the rules for season 2.