trust me, my entire guide is a bit dated. there's probably parts i haven't touched since i posted it last June, and just a little bit has happened since.
but yeah, you can use the ExtraBones. it turns out that FortWaffle's bone adding program basically copies the entire model, pastes it to the end, changes a few pointers, and adds the bones into the data at the end. if you want to change it, then open a model in hex before you add the bones, write down where it ends, add the desired amount of bones, re-open it in hex, go to where you wrote down, and you'll see the header data of the model again. just go down to the bone data in the second model data, and make the changes you want, and it will change it. this is why i was under the assumption that you couldn't hex changes after adding bones, i never realized that there was a second set of data that was read.
but if you want to use the ExtraBones, get TheShyGuy's Bone Tree Editor program, put the ExtraBones where you want, and change the BoneRef's in Tabuu, and you're good to go. i did test out if it they could be used as the important bones (TransN, HipN, and ThrowN), and from what i remember, they all worked. it was shortly after that i went back to school and have done almost no hacking since.
yeah, the Pokepark models can be fun to work with sometimes. the shield problems are because of a lack of a ThrowN in the proper index, and for the grab glitch it should be a HipN problem.
Ghork and xxmasal22xx, for the shield, you probably can get it to work, i'm just a little unsure as i haven't had time to test this yet. but using TheShyGuy's Bone Tree Editor, you can take an ExtraBone and attach it to where you want (try attaching it to the third bone first, it should be equivalent to the HipN), then rename that to ThrowN, and change the ThrowN BoneRef in Tabuu accordingly. i think i did get it to work on one model, but i can't remember if it was the shield or the TransN and HipN i was testing.
KingJigglypuff, it's probably a HipN problem you're having. if i remember correctly, the Pokepark models can match up better to Brawl models if you rename the bones like this; TopN > TransN > HipN > then the rest of the structure should branch out from there. a ThrowN bone will also help, but the lack of one shouldn't cause freezings, it should just make it so the model doesn't move/follow how it should be thrown while being thrown.
and actually, we can use the ExtraBones, they just won't be attached to the model in any way, which makes for a perfect ThrowN bone. the problem is getting them where you need them to be.
basically, it's exactly the same as putting the model on a regular character, the only difference is that you only need to make a few animations instead of a ton.
yes, they may have certain glitches, but not nearly as many as a character port does. and yes, it will t-pose until you make new animations or rename bones (but renaming bones could cause some ugly stretching).
is the problem just when you try doing certain models? i know that with small models like items, it's a bit picky as to what it will and won't work with. what is the model that is giving you the error?
and also, when you export the model, it should be named model.mdl0, not mdl0.mdl0.
those aren't new slots, but certain characters over others. if you look at his CSS at 4 seconds in, not all the regular Brawl characters are in there. i've made a list for you of which new characters he has over regular Brawl characters.
Wolf - Lloyd Metaknight - Gray Fox Ike - Cloud Marth - Sephroth Lucario - Mewtwo Luigi - Silver DK - Shadow Pikachu - Knuckles Jigglypuff - Wisp Yoshi - Tails
some are pretty old projects, and never got too far.
so to answer your question, no, it's not possible to add character slots. it is possible to fully replace characters, but not add new slots.
for vertexing, this is the one i use. it seems easy and basic enough, but you'll definitely have to play around with 3ds max for a bit to get used to it. but once you do, it'll be pretty easy to vertex.
as for model porting, i happen to have a small guide on how to do so. and by small, i mean huge. it includes almost all glitches that could happen to a model port, and how to fix them. it also has a brief hexing guide, and a guide for using Tabuu (a program).
as for the rest, just check out the top link. you'll find just about anything you'll need.
no, articles are a bit different. Tabuu is the easiest way to fix it. open the FitCharacter.pac in Tabuu, then go to FitCharacter/MiscData[0] > Sections > data > Article. then it will show which articles are defined to certain bones, but keep in mind that it may not show all of the articles, just the ones that are attached to certain bones (like Link and TL only having 3 show up in Tabuu, when they have a lot more). once you open the first Article tab, a few more tabs labeled Article will appear. click on one of those, and the right hand window will show some options. what you want to change is BoneID. i'm not entirely sure of an easy way to check which Article is which article, but the BoneID kind of helps. if you know that it attaches to the HaveN bone, then look for the HaveN bone ID of the character you're replacing. for example, i'm pretty sure Toad is attached to Peach's HaveN, but she has 2 Articles attached to the HaveN bone (ID 101). what i'd suggest doing is change 1 of the ID's, then testing in game to see if something changes. oh, and to make changes work in Tabuu, make the change, then right click the tab you just changed in the left window, click 'Open Hex View', then in the 'As Int' tab at the bottom of the new window, change the number to match what you changed it to before. but make sure you change the right number. for the BoneID in the Articles, it's the 3rd set of numbers in. click it, then change the number. then go back to the top, right click the FitCharacter/MiscData[0], then Save File. it will crash after a moment, but it does save the changes.
first off, you need 22 bones added to the PT, he has 47, and Snake has 69. but that shouldn't cause issues unless you shield, but you should probably add the bone in anyways.
second, when exactly does it freeze? on the CSS when selected? after you choose the stage but before the fight starts?
it's also possible that it's a file size issue. the PT's files are incredibly small, and Snake's are a bit bigger. what's the size of the FitSnake00.pcs when it has the PT model in it?
the way you would do that is, in BrawlBox, in the model previewer you find the polygon that you want to remove. once you find it, remember the number it is, then in the MDL0 info (expand the FitPikmin00), expand the Polygons folder, click the polygon you want to remove, and it will show you the offset for that polygon. it will be in decimal, so convert it to hex, and go there in a hex editor. then, go below the header data (either 0x64 or 0x68, can't remember which, but it will show in the header itself), and zero everything out. just be a bit cautious though, some polygons can't be removed without causing issues.
but you won't be able to get rid of Olimar's nose that way, since it's part of his Polygon1, unless you want the head and hands gone as well. you'll just have to vertex/texture it out.
i think the BodyN is specific to Metaknight. it's the bone below his HipN. i think a few of the lower indexes might be more character specific than the first ones. but you can always compare which bones go to which part of the model, just open the FitCharacter.pac in Tabuu and the FitCharacter00.pac/pcs in BrawlBox, then look at the BoneRef in Tabuu and find the corresponding index in the bone structure in BrawlBox.
the TopN is just an empty bone. with the way that Brawl applies animations, nothing gets applied/can be applied to the TopN or the first bone of the structure, which is why all Brawl models have a TopN. it can make certain model imports just that much more fun to try to deal with, because not all games do it like that, especially with items.
you open the FitCharacter.pac file (the PSA file). it won't show the bone structure like it does in BrawlBox, but it will have an area to change everything.
in Tabuu, go to FitCharacter/MiscData[0] -> Sections -> Data -> Misc -> BoneRef. this is where you define where certain bones are located. it most likely won't show the names, it will basically say 'no reference model loaded', so here's a pic of which references are which (they're pretty much universal, and the first 5 are the only ones i ever change).
you mainly want the TransN, HipN, and ThrowN to match the new model, although the XRotN and YRotN bones can also be useful (if the model has enough spare bones). to change the references, click the one you want to change in the left window, and then in the right window it will show a spot called Bone Index which is what you want to change. so change that to what you want, then in the left window, right click the one you just changed (it will turn red to signify something changed), click 'Open Hex View', then change the current number to what you just changed it to in the 'As Int' tab at the bottom of the new window (and then click in one of the other tabs just to make sure the change goes through). and now it will work. then to save, right click the FitCharacter/MiscData[0], and click Save As. it will then crash, but it saves the changes.
with the animations, that should be the best. that way you don't have to spend as much time fixing the animations as making them.
and you can always pm me if you have questions or if you need help, i usually check here a few times through the day.