Is this a good team for Pokemon Emerald?

I'm recently found my old Pokemon Emerald cartridge and am playing through it again. I haven't played in a while so I was wondering if this would be a good team to use to beat the elite four

Swampert:
Earthquake
Surf
Ice beam
Iron Tail

Gardevoir:
Psychic
Thunderbolt
Fire Punch
Shadow Ball

Breloom:
Sky uppercut
Solarbeam
Giga Drain
Sludge Bomb

Swellow:
Aerial Ace
Fly
Steel Wing
Return

It really depends on the level (you might want to grind a little), but it seems solid :) .
Nothing against your Gardevoir which in theory could handle Phoebe and Wallace on its own, but I'd recommend you to fill the two remaining slots with a dark-type Pokémon to battle Phoebe, and an actual electric type to battle Wallace (you know, Same-Type Attack Bonus and everything) .

Like maybe

Sharpedo:
Crunch
Waterfall
Dive
Blizzard

Manectric:
Thunder
Bite
Iron Tail
Strength

I have experience in using both and yes, these Pokémon are not half bad :) .

However (but this is something I leave to your judgment) I'd advise you to teach them Ice Beam and Thunderbolt instead of Blizzard an Thunder. Yes, the moves you chose are more powerful. But they also have two significant drawbacks: they are more likely to miss and have less PP (which can be critical if you're tackling multiple trainers in a row) . IIRC, you can get TMs with both moves in the Mauville Game Corner.

Alright, thanks a lot. wish me luck!

You might want to get a Pikachu for Wallace.