If Mon Mothma is not available, 'General Dodonna' would be a suitable alternative.
Position Squadrons carefully to avoid enemy 'Intel' and 'Escort', if possible.
Prioritise Rhymer as a target, if shielded by 'Escort' then simply try to Engage as many enemy squadrons with your own squadrons - put your own squadrons in one at a time if need be, that's four turns minimum reducing the Rhymerball's attack capability.
If enemy is shielded by 'Intel', move into a position that is outside of the range of the 'Intel' squadron but within range of other squadrons. A-Wings speed will be useful for this.
If enemy 'Intel' squadrons move to counter your engaging squadron, repeat the process next turn with another squadron.