My friend is planning to start a campaign soon that is fairly low magic. I had already made two characters, an unconventional and reflavored druid and a telepathic beast barbarian. I made a pallid elf rogue character because I was a bit concerned about the fact that both of those characters were involved heavily with magic. The problem though is that pallid elves, and many other races have innate spells (why is it so hard to make nonmagical characters). The DM is pretty chill and happy with letting us change stuff for this campaign, which he wants to feel like an anime, and wants martial characters to be as strong if not stronger than casters. I was thinking of changing the feature to something equal in power, but I'm not sure what would be equal in power to the pallid elf's innate spellcasting, so I would like ideas. Thank you.

You could use:

• Mask of the Wild. You can attempt to hide even when you are only lightly obscured by foliage, heavy rain, falling snow, mist, and other natural phenomena, from Wood Elf

or 

• Damage Resistance. It would have to be one of the less common damage-type, Radiant seems thematic, maybe Cold would fit as well.

or 

• Weapon Training. Proficiency with longbows & longswords, from other Elves.

or

• Telepathy. Range of 30 ft. That would probably be roughly equal in power.

How about the hobgoblin’s Fey Gift trait? Elves and goblinoids are supposed to share the same original homeland and they were both fey at one point so it kinda fits, and that would probably be about on par with loosing the plaid elf’s spellcasting. I mean, light is situational at best since they already have darkvision, but even only once per long rest, sleep can be super useful in lots of situations and invisibility is no joke.

Ooh! I really like that fey gift idea, especially because the character is supposed to be a good strategist. The only problem is that it still feels a bit magical, but I can probably flavor that away.

As for @Agilemind 's ideas, mask of the wild is much more situational than sleep or invisibility, damage resistance could work, and be cool, but I just love that fey gift idea more. Weapon training post Tasha is just a bunch of tools, which seems kinda awkward. Telepathy feels too magical for the setting. 

Sleep is pretty useless beyond level 3, Light is situational, but Invisibility is pretty decent utility. Mask of the Wild depends on the campaign but it you don't have anyone with invisibility b/c low magic setting it would probably be pretty useful - being able to jump into a bush to hide is often the next easiest way to avoid guards if you can't teleport or be invisible. Though if you're campaign is no-sneaking focused then neither invisibility nor Mask will be much use. 

Longbow proficiency can be pretty sweet on a Rogue if you're going for a sniper-type build, which is why I included it. Though for a melee-rogue it's not that useful, though again if you've got no spells at all then tool proficiencies will be much more valuable than normal - Disguise Kit replaces Disguise Self, Carpenter's Tools would be useful to build bridges / ladders to make up for movement deficits, Forgery Kit to create documents to convince people to help you rather than relying on charm spells, or Mason's Tools to dig out dungeons rather than Stone Shape.

Quote from Agilemind >>

Sleep is pretty useless beyond level 3

Ehh. It's very situational, but it's not useless

BBEG uses mind control on hapless civilians to throw at the party? An upcast sleep takes them out of the equation. Any time there are lower-level enemies you for some reason don't want to kill, it's a strong option