I do mind when it has no use.
Either way, to answer your question, which would've been a good reason to bump... I believe only 3 suits have effects, the crab, who raises your defence by a 1.25 multiplier, the jelly costume who over the second heals 0.5 health until it reaches half of your health, and finally the Urchin costume who deals out 0.4 damage per hit.
You have 5 health when you start the game and 10 when you have all egg upgrades (1 health per egg).
To help the math even more...
A normal Nautilus has 4hp, your normal energy shot deals 1 damage, and your charged energy shot 1.5 damage.
If you have more questions, I'd love to answer them, if I can.