Beef #1: Ramming

[Taqwus]

Yup. Ionic weapons would really ruin a rammer's day. So would anybody else having a speed advantage (or even parity, barring huge numbers) and a maximum-weapons-range / don't-get-hurt tactic.

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-- The thing that goes bump in the night

[dmm]

Taqwus and Neo:
True and true, rammers would need greater numbers. But remember that they are cheaper than regular ships, and can take out ships much larger than themselves, so you would normally be launching a swarm of small ships at a few large ships. Also, ramming specialists would only need to research armor and propulsion, so that, all other things being equal, they'd be the fastest ships.

And of course, as has been pointed out before, every strategy has an effective counter-strategy. Rammers would dread a crystalline race with multi-targeting.