So I'm a long time X-wing player who dabbles in Imperial Assault. As in I've played it three times since it came out, mostly campaign mode.

There is a regional nearby this weekend that may have pretty light attendance, so I'm thinking of going because even if people wipe the floor with me I'll probably get some prizes and maybe learn a bit more about how to play.

I have the core set and the hoth expansion. I was thinking of inviting a friend who has done the campaign modes with me but has none of the stuff and we could play different factions.

But can my friend compete without a core set? In X-wing you don't need much to go to a tournament (Dice, movement templates, range ruler, asteroids, tokens)

What would my friend need at a minimum to be able to compete in terms of the accessories?

Contact the venue to determine if they are using preprinted maps. If not, that is the biggest hurtle your friend has to get over.

Currently, each player is supposed to have all of the tiles with which to make the maps. You personally are also in need of the tiles from Twin Shadows.

Technically, the minimum products needed to participate in an Organized Play event are:

MAPS

Core set

Twin Shadows

Return to Hoth

MISSIONS:

Stormtrooper villain pack

Leia hero pack

Twin Shadows

And this sadly is one of the reasons why X-Wing is so much more popular than Imperial Assault. For IA you DO need 'much' Everything listed above is necessary and with that you can build a pretty good trooper spam list, but need a few other blister packs to venture out into some of the other more popular lists. We are all hoping that FFG will eventually somehow fix this (maybe supply printed tournament maps with the kits) but until it happens we are definitely handicapped.

But can my friend compete without a core set? In X-wing you don't need much to go to a tournament (Dice, movement templates, range ruler, asteroids, tokens)

All those x-wing components you listed only come in the core set, so each player does need a core set to play in a tournament, just like IA. The only difference is the x-wing core costs 40 msrp vs IAs 100.

That being said, unless more than half of the players don't have map tiles, there will always be leftover tiles each round, so if you let the TO know it should be fine, IA is pretty desperate for warm bodies.