The enemy sniper's have 441 to 514 ACC. You'll want to match that number to be safe or beat it by 100 to be certain. Luckily, the stage takes place on a City field so you can get a +10% bonus to EVA by using a unit that has City as their Field of Expertise.
Here are a few examples of Short-Range unit stats on a City field with a 1* EVA item and minimum Training Range bonus.
| Ayame Shishizawa |
HP | 1098 |
ATK | 1150 |
DEF | 418 |
EVA | 345 |
B-Rank Lvl 10 Ayame - 456 total EVA
(+2% item, +6% formation, +10% FoE, +2 TR, 385 base) = 385 * 1.18 + 2 = 456
S-Rank Lvl 20 Ayame - 497 total EVA
(+2% item, +6% formation, +10% FoE, +2 TR, 420 base) = 420 * 1.18 + 2 = 497
| So Shiguchi |
HP | 1100 |
ATK | 1210 |
DEF | 440 |
EVA | 363 |
B-Rank Lvl 10 So - 465 total EVA
(+3% skill, +2% item, +6% formation, +10% FoE, +2 TR, 383 base) = 383 * 1.21 + 2 = 465
S-Rank Lvl 20 So - 492 total EVA
(+3% skill, +2% item, +6% formation, +10% FoE, +2 TR, 405 base) = 405 * 1.21 + 2 = 492
| Sumiko Omiya |
HP | 1045 |
ATK | 1210 |
DEF | 440 |
EVA | 363 |
B-Rank Lvl 10 Sumiko - 458 total EVA
(+2% item, +6% formation, +2 TR, 423 base) = 423 * 1.08 + 2 = 458
S-Rank Lvl 20 Sumiko - 498 total EVA
(+2% item, +6% formation, +2 TR, 460 base) = 460 * 1.08 + 2 = 498
| Mahko Minamoto |
HP | 1045 |
ATK | 1150 |
DEF | 418 |
EVA | 345 |
| Karen Nishido |
HP | 1045 |
ATK | 1150 |
DEF | 418 |
EVA | 345 |
B-Rank Lvl 10 Mahko/Karen - 428 total EVA
(+2% item, +6% formation, +2 TR, 395 base) = 395 * 1.08 + 2 = 428
B-Rank Lvl 20 Mahko/Karen - 467 total EVA
(+2% item, +6% formation, +2 TR, 431 base) = 431 * 1.08 + 2 = 467