To dream that you have a seizure indicates that you lack the power to take charge of certain aspects in your life.
To dream that you are experiencing adversity means that you will experience defeat and enduring misfortune.
To dream of others enduring adversity means that someone close to you may be met with some malady.
To dream of being tackled unexpectedly is a clear indication of either an expectation of being interrupted in the middle of an enjoyable moment, or the incompletion of an important goal due to your sense of duty or obligation. Note the surrounding aspects of a dream in which you are tackled, as this will point you in the direction of the issue in your waking life; are you being tackled at work, home, in the middle of a fun activity, or an actual football game?
To dream of being tackled or tackling someone in a football game implies a competitive streak. This is usually with a sibling, but it could also be at work.