Looking For Equipment Guide

From maybe 50-90 also do stats like int and mnd ect. effect the avatars in anyway at all or does the gear have to say specifically for avatars?

more or less: austere/artifact armor -> yinyang robe/relic armor -> empyrean armor+1/+2.

For accessory slots try to get Evoker's ring, the job specific accessories from Abyssea, and any MP+ gear.

INT/MND don't make a difference from what I've seen. Only specific "Avatar:" gear and "Summoning Magic+"

Focus should be:
1) -avatar perpetuation gear (HQ elemental staffs help a lot with this)
2) -blood pact gear (YinYang Robe, Austere Hat/Robe)
3) summoning magic skill (for elemental siphon, it enhances avatar accuracy to blood pact: Rage and adds duration to blood pact: Ward)
4) gear that enhances avatar's accuracy/attack/magic attack (not a lot to choose from at lower levels iirc)
5) A good idle set and resting MP set

If you are leveling Summoner the old fashion way (i.e. in old style parties) be prepared to main heal or back up heal.

If you have a job that already has access to abyssea I would recommend starting on the af3+1/2 sets, they are amazing for summoner.

INT and MND don't affect your pets unless it specifically says "Avatar: INT+10"

As for gear sets, from level 50-75 you only have two choices of gear to use, Austere and Artifact 1. Mix and match them. Have a -perp set, -BP recast delay set, and a Summoning Magic skill+ set.

As for 75+, here is what I currently use.
If you have time/patience to do Magian Staves, do so. You can also aim for a Fay Crozier with -3 perp so you don't have to lug 8 staves around. Hope this helps~

Just to add to Vileplume's item sets for 75+, stick Eidolon Pendant and Caller's Sash in the Neck/Waist slots respectively for Magic BP. Eventually, once Mujin Obi becomes more common, stick that in waist for physical BP. For earrings, I stick Moonshade and Gifted on full-time (Caller's Earring is fine without one of these, but I hit the -BP cap on other items so don't use it).

For physical AND magical BP sets, once you get full +2, reports have come out that macroing all 5 pieces and stacking Blood Boon works to increase your damage on average (they won't proc everytime of course, but average DoT will increase).